Toyota's have "preferred" & "acceptable" grades e.g.my Avensis 1.8 preferred is 0W20 but 5W30 is acceptable (albeit will likely have a very small impact on fuel efficiency) - perhaps your cars are similar.? So for my car a top up with 5W30 is OK but if I was doing a complete oil change then 0W20 would be better.
Well, its probably better for the maker, since they recommend it.
Whether its better for the punter will depend on the extent to which individual and corporate interests align.
But probably not much in it either way.
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Toyota's have "preferred" & "acceptable" grades e.g.my Avensis 1.8 preferred is 0W20 but 5W30 is acceptable (albeit will likely have a very small impact on fuel efficiency) - perhaps your cars are similar.? So for my car a top up with 5W30 is OK but if I was doing a complete oil change then 0W20 would be better.
Well, its probably better for the maker, since they recommend it.
Whether its better for the punter will depend on the extent to which individual and corporate interests align.
But probably not much in it either way.
They recommend it because it is better for the engine/fuel economy. The recommendation may also vary according to local temperatures, duty cycle etc.
I don't really see Toyota getting rich by specifying one over the other?
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Well, its probably better for the maker, since they recommend it.
Toyota (like all makes do not actually manufacture oils). There will be an oil "branded" as Toyota but it will no doubt be bought in from the lowest bidder (just like all car parts).
The only oil I have ever bought from the manufacturer/dealer was VW Quantum simply because it obviously met the relevant VW standard and it was also cheaper than any identical spec oil from a local parts shop. Considering that one of the VW's I had (from new) was still using no oil after 113,000 miles the oil was clearly up to the job. When I happened on the car 20 years later in a Tesco car park the car was showing just over 200,000 miles and since it had been the the current owner and his brother for the last 17 years he was pretty certain the engine was original and unmolested and still using no oil.
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An engine may hold ~5L of oil. If it consumes none, the oil will be there until next changed.
If the level falls and a top up of (say) 0.5L is required, it is almost irrelevant what is used as a top up (possibly even that which fries your chips) as 90% will still be the recommended formulation.
My suggestion - buy oil which meets the spec of the most expensive vehicle and use it to top up the rest.
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An engine may hold ~5L of oil. If it consumes none, the oil will be there until next changed.
If the level falls and a top up of (say) 0.5L is required, it is almost irrelevant what is used as a top up (possibly even that which fries your chips) as 90% will still be the recommended formulation.
My suggestion - buy oil which meets the spec of the most expensive vehicle and use it to top up the rest.
Youv'e not heard what happens when you mix mineral and vegetable oils in an engine?
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Toyota's have "preferred" & "acceptable" grades e.g.my Avensis 1.8 preferred is 0W20 but 5W30 is acceptable (albeit will likely have a very small impact on fuel efficiency) - perhaps your cars are similar.? So for my car a top up with 5W30 is OK but if I was doing a complete oil change then 0W20 would be better.
Well, its probably better for the maker, since they recommend it.
Whether its better for the punter will depend on the extent to which individual and corporate interests align.
But probably not much in it either way.
They recommend it because it is better for the engine/fuel economy. The recommendation may also vary according to local temperatures, duty cycle etc.
I don't really see Toyota getting rich by specifying one over the other?
In some markets (notably the USA) they have to meet fleet fuel economy targets, or get fined.
Published fuel economy figures are also good for marketing. So yes, skinny oil helps Toyota "get rich"
In general skinny oil optimised for fuel economy also helps the punter get/stay rich.and this will be the best choice for most punters.
If the punters primary concern is minimising wear, a minor consideration for most, since most engines go to the sc***yard with plenty of life left in them, then a thicker oil may be a better choice.
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Suzuki Jimny ’recommend’ 0W16 oil for Europe and Israel. Yet the span goes all the way to 5W30, irrespective of where in the world or climate.
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If the punters primary concern is minimising wear, a minor consideration for most, since most engines go to the sc***yard with plenty of life left in them, then a thicker oil may be a better choice.
One contributor on here some years ago who worked in the oil industry explained it very clearly.
People may think thick oils are good but with improved products thick is not needed for getting good lubrication of parts. In addition with modern manufacturing techniques tolerances are much tighter and thin oils are needed to ensure good oil flow in a cold engine.
I accidentally proved the latter some years ago.
Newly built ford x-flow race engine. All the right (same bits) bits but bigger pistons gave 1760cc instead of 1600cc.
I always ran them in on mineral oil for the first 100 miles before changing to my usual oil, used 10w40 which was Ford recommended viscosity for the late production of the engine. I also changed the oil after about 30 miles to check there was nothing amiss with the engine and this also helped clean out the products used during the build (graphogen makes new oil look 10,000 miles old in a few seconds).
So filled the dry sump with 10w40 Ford Mineral and the engine ran beautifully with exactly the oil pressure I expected. After 30 miles approx dropped the oil but the Ford garage had no 10w40 so with a choice of 5w30 or 20w50 I went for the 20w50 since that was Fords spec before changing to 10w30. Started engine and only about 20 psi of pressure instead of the usual 70 psi with a cold engine, very worried. But as the engine warmed up the pressure increased and eventually got to 70 psi, when hot it ran at a perfectly normal 60 psi at about 3000 rpm, very confused. Left it overnight and tried it again the next day, exactly the same. So before taking it out on the road I decided that the thicker oil was probably the issue and I should get some 10w40 but Ford garage still had none. Took decision to drop 1/2 the 20/50 and fill with 5w30 the mix seeming to average out at about 10w40. Started engine and pressure back to normal. Obviously the tighter tolerances used were not compatible with the old oil specs. After reaching 100 miles it went onto my usual 10w40 (probably Duckham's QXR at that time).
Should add that was in late 1990. That engine ran in the Caterham until the end of 2002 with no more issues with regards to oil pressure. It did have a couple of precautionary rebuilds during which the cam was changed a couple of times plus I fitted a long stroke crank that increased the capacity to 1860cc.
Mate had the engine and ran it until 2008 when he sold it to a bloke in France.
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If the punters primary concern is minimising wear, a minor consideration for most, since most engines go to the sc***yard with plenty of life left in them, then a thicker oil may be a better choice.
One contributor on here some years ago who worked in the oil industry explained it very clearly.
People may think thick oils are good but with improved products thick is not needed for getting good lubrication of parts. In addition with modern manufacturing techniques tolerances are much tighter and thin oils are needed to ensure good oil flow in a cold engine.
I accidentally proved the latter some years ago.
Newly built ford x-flow race engine. All the right (same bits) bits but bigger pistons gave 1760cc instead of 1600cc.
I always ran them in on mineral oil for the first 100 miles before changing to my usual oil, used 10w40 which was Ford recommended viscosity for the late production of the engine. I also changed the oil after about 30 miles to check there was nothing amiss with the engine and this also helped clean out the products used during the build (graphogen makes new oil look 10,000 miles old in a few seconds).
So filled the dry sump with 10w40 Ford Mineral and the engine ran beautifully with exactly the oil pressure I expected. After 30 miles approx dropped the oil but the Ford garage had no 10w40 so with a choice of 5w30 or 20w50 I went for the 20w50 since that was Fords spec before changing to 10w30. Started engine and only about 20 psi of pressure instead of the usual 70 psi with a cold engine, very worried. But as the engine warmed up the pressure increased and eventually got to 70 psi, when hot it ran at a perfectly normal 60 psi at about 3000 rpm, very confused. Left it overnight and tried it again the next day, exactly the same. So before taking it out on the road I decided that the thicker oil was probably the issue and I should get some 10w40 but Ford garage still had none. Took decision to drop 1/2 the 20/50 and fill with 5w30 the mix seeming to average out at about 10w40. Started engine and pressure back to normal. Obviously the tighter tolerances used were not compatible with the old oil specs. After reaching 100 miles it went onto my usual 10w40 (probably Duckham's QXR at that time).
Should add that was in late 1990. That engine ran in the Caterham until the end of 2002 with no more issues with regards to oil pressure. It did have a couple of precautionary rebuilds during which the cam was changed a couple of times plus I fitted a long stroke crank that increased the capacity to 1860cc.
Mate had the engine and ran it until 2008 when he sold it to a bloke in France.
I would hope your authoritative source contributor didn't say "tolerances" (which means the range of variation from the spec. that is accepted, or tolerated) when they meant "clearances", but it seems a common misuse, so maybe they did.
It seems plausible that "tolerances", (strictly speaking, as one should) will have been reduced, continuously since, say, the early 70's, reflecting more accurate manufacture using improved CNC machinery.
OTOH its not obvious (to me) that clearances will have reduced continuously, or why they would. Presumably there will be an optimum below which there will be more shear in the oil, more boundary drag, more frictional losses and a higher probability of actual contact wear, so there would be significant disincentives below such an optimum.
To test the effect of viscosity on wear, one has, rather obviously, to measure wear at different viscosities. Your anecdote referencing oil pressure does not do this, and wear can not be inferred from it.
When I last looked I found a few studies that measured wear at different viscosities. These were in commercial vehicles, where the stakes (and the viscosities) are higher, and the punters perhaps less easily convinced by marketing. Generally wear was higher at the lower viscosities, as one would expect if viscosity is the only variable in play.
However, viscosity will not always be the only variable in play. If a skinny oil has a better anti-wear package, it may show lower wear than a thicker oil, even though less contact will occur with the thicker oil.
I dont remember finding any tests of car oils, but this is not especially surprising, since IF the skinny recommended oil with better fuel economy had worse wear figures, it wouldn't be in any stakeholders interest to advertise this
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<< People may think thick oils are good but with improved products thick is not needed for getting good lubrication of parts .... and thin oils are needed to ensure good oil flow in a cold engine. >>
A thin oil will clearly give a viscosity advantage when starting a cold engine, but presumably that is somewhat offset by the thin oil draining down faster, leaving a thinner film on cylinder walls etc.?
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<< People may think thick oils are good but with improved products thick is not needed for getting good lubrication of parts .... and thin oils are needed to ensure good oil flow in a cold engine. >>
A thin oil will clearly give a viscosity advantage when starting a cold engine, but presumably that is somewhat offset by the thin oil draining down faster, leaving a thinner film on cylinder walls etc.?
Dunno. Never seen any convincing evidence on either point, the "clearly" advantage, (which IS contested) or the drain down.
EDIT : Just came across this
www.kingbearings.com/wp-content/uploads/2014/10/EC...f
"In addition to friction reduction, low viscosity oils cling less to the connecting rod
surface, thus reducing effective rod weight. Since connecting rods perform accelerating
(reciprocating) movement, the power required for the inertia forces is proportional to the
rod weight. With less oil adhering to the rod surfaces, less power is required for their
movement."
That seems to confirm that low viscosity oils drain down more, at least on exposed surfaces, but I'd doubt this would apply to bearings, which I would expect to be oil filled whatever the viscosity. Maybe there would be some difference in oilways.
The article as a whole (though not peer-reviewed research, irritatingly mis-using "ecological", and with a key omission mentioned below ) seems an OK mildly technical summary of this area of controversy The graph showing the effect of viscosity on Minimum Oil Film Thickness (MOFT) for different clearances has the commentary (for thin oil)
"As seen in Fig.2, the value of min. oil film thickness may drop to critical levels at low
rotation speeds - particularly in high load high performance engines."
They say thin oils do ok for low clearances (below 0.0025 inches) but not above.Thick oils are better above 0.0025 inches, but annoyingly they dont say anything about how thick oils do below 0,0025 inches,
Edited by edlithgow on 01/11/2023 at 03:52
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Suzuki Jimny ’recommend’ 0W16 oil for Europe and Israel. Yet the span goes all the way to 5W30, irrespective of where in the world or climate.
There's good logic that climate doesn't matter as far as the hot viscosity goes - as the temperature inside the engine is about the same once the engine is warmed up regardless of whether you're in Northern Europe or Canada in winter or Southern Europe or Australia in summer.
The OP needs to establish three things about each engine as recommended by its manufacturer - the viscosity, eg 0W-30 or 5W-40 etc - the grade, eg ACEA-C3 or ACEA-A2 etc and the manufacturers technical standard, eg VW 507.00, etc - the grade and technical standard are absolutes but many oils, particularly "good" brands cover several grades and standards - the viscosity can be fudged a bit for top-up oil.
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Thanks All, plenty for me to consider there.
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I would hope your authoritative source contributor didn't say "tolerances" (which means the range of variation from the spec. that is accepted, or tolerated) when they meant "clearances", but it seems a common misuse, so maybe they did.
It seems plausible that "tolerances", (strictly speaking, as one should) will have been reduced, continuously since, say, the early 70's, reflecting more accurate manufacture using improved CNC machinery.
Lets just say that tolerances of the clearances are much better controlled now than they were last century.
A couple of examples.
A Mk 2 Escort 1600 had bore between 80.947 and 81.007, that's 0.06mm
A 2004 Focus with the 2 litre Zetec engine had a bore between 84.800 and 84.830, that's 0.03mm.
In just over 20 years the manufacturing tolerance had halved.
A Mk2 Escort 1600 had a Crank Endfloat between 0.075 and 0.280, that's 0.205mm.
A 2004 Focus had a Crank Endfloat between 0.090mm and 0.260mm, that's 0.170mm.
In just over 20 years the manufacturing tolerance was about 20% reduced.
That is why a more modern Ford engine used 5w30 instead of the 10w40 of the earlier cars.
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I would hope your authoritative source contributor didn't say "tolerances" (which means the range of variation from the spec. that is accepted, or tolerated) when they meant "clearances", but it seems a common misuse, so maybe they did.
It seems plausible that "tolerances", (strictly speaking, as one should) will have been reduced, continuously since, say, the early 70's, reflecting more accurate manufacture using improved CNC machinery.
Lets just say that tolerances of the clearances are much better controlled now than they were last century.
A couple of examples.
A Mk 2 Escort 1600 had bore between 80.947 and 81.007, that's 0.06mm
A 2004 Focus with the 2 litre Zetec engine had a bore between 84.800 and 84.830, that's 0.03mm.
In just over 20 years the manufacturing tolerance had halved.
A Mk2 Escort 1600 had a Crank Endfloat between 0.075 and 0.280, that's 0.205mm.
A 2004 Focus had a Crank Endfloat between 0.090mm and 0.260mm, that's 0.170mm.
In just over 20 years the manufacturing tolerance was about 20% reduced.
That is why a more modern Ford engine used 5w30 instead of the 10w40 of the earlier cars.
That's misleading - the Escort Kent engine may have had 0.06mm variation in bore size but pistons were available with different marginal diameters so the real variation in clearances would be much less - in any case, the published variation was often used to allow an over-capacity engine to be bored out to the next size limit, eg using the same block as the "cooking" Escort, the Escort RS1600 had nominal bore sizes to give 1601 cc which allowed it to be bored out to the next size limit which was 1800cc
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The RS 1600 did use the 81.007mm bore to allow a 1601cc capacity but if I remember correctly that put it into the 1600 to 2000 cc class and no cross flow block of that period would manage such a rebore reliably.
The Escort Mexico's used in the World Cup Rally of 1970 use x-flows with a 1800cc capacity but there were highly modified blocks which had most of the internals cut out and then new ones welded in which allowed for the almost 86mm bore required for 1800cc. No production block of that time had the capacity.
The RS1600 rally cars (and later RS1800's) used a Cosworth alloy block (designed by Brian Hart) which allowed a 2 litre capacity with a standard stroke.
The X-Flow block I used was designated as a AX block and came from South Africa. There was a huge number of urban myths about these but it seems they were developed locally for a diesel x-flow variant. They would bore safely to 87mm. When I bought mine they were about £200 new but mine was already at 83.5mm and had a damaged bore, paid £10. New set of 85mm Omega pistons and a rebore and voila, a very safe 1760cc (1860cc with the stroker crank).
Last time I saw one for sale they wanted over £1000 for it.
Today a new x-flow block from Ford Racing which is allegedly even better than a AX retails at £3960.
I bought my 2 litre Zetec as a complete crate engine ready to fit (it did need some ancillaries changing to go into the Caterham instead of a Focus) from Ford for £700 + vat.
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I would hope your authoritative source contributor didn't say "tolerances" (which means the range of variation from the spec. that is accepted, or tolerated) when they meant "clearances", but it seems a common misuse, so maybe they did.
It seems plausible that "tolerances", (strictly speaking, as one should) will have been reduced, continuously since, say, the early 70's, reflecting more accurate manufacture using improved CNC machinery.
Lets just say that tolerances of the clearances are much better controlled now than they were last century.
A couple of examples.
A Mk 2 Escort 1600 had bore between 80.947 and 81.007, that's 0.06mm
A 2004 Focus with the 2 litre Zetec engine had a bore between 84.800 and 84.830, that's 0.03mm.
In just over 20 years the manufacturing tolerance had halved.
A Mk2 Escort 1600 had a Crank Endfloat between 0.075 and 0.280, that's 0.205mm.
A 2004 Focus had a Crank Endfloat between 0.090mm and 0.260mm, that's 0.170mm.
In just over 20 years the manufacturing tolerance was about 20% reduced.
That is why a more modern Ford engine used 5w30 instead of the 10w40 of the earlier cars.
Not sure this makes much sense.
The tolerance itself should have little influence on recommended viscosity, except to the extent that it influenced the clearance.
If narrower clearances require thinner oils, it would be the minimum clearance that would determine how thin you needed to go, (or could get away with) not how much it varies,
Specifying thicker oils for greater tolerances without reference to the minimum clearance would imply that the thicker oil can also accommodate the minimum, whatever it is
Bore clearance cant be deduced from your example. The minimum endfloat is actually greater in your newer example, but endfloat perhaps isn't conventionally considered to be the main influence on oil choice, which would probably be bearing clearances
I found an example of a couple of Honda Accords, 1985 and 2012. inches I'm afraid, because Americans. There doesn't appear to be a consistent shift in minima or tolerances.Some have decreased, some have increased.
One would have to analyse quite a few engine pairs to tease out any general trends in clearances, and the influence of such general trends on oil recommendation would still be a matter of speculation.
There isn't much doubt, though, that skinny oils use less fuel, and that that is what they are for.
bobistheoilguy.com/forums/threads/have-engine-tole.../
Edited by edlithgow on 30/10/2023 at 23:45
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Unless you're planning on driving it at below about minus 20, 5w30 will be fine especially if just topping up.
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The sticky thread at the top of the forum has a lot of oil info. Whether it's still valid I don't know as it's quite old now.
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There isn't much doubt, though, that skinny oils use less fuel, and that that is what they are for.
Not only that. When Ford introduced the new Zetec engine in the early 90's they specified 10w40 oil but there were issues with the hydraulic lifters. They changed the oil spec to 5w30 and no more lifter issues.
When the later Zetec SE 1.2, 1.4, 1.6 & 1.7 (the Yamaha designed one used in the Fiesta etc) and the Blacktop 1.8 and 2 litre Zetec (developments of the Mondeo Silvertop Zetec) were introduced in the the Mk 1 Focus they had changed to solid lifters but for economy and emissions the 5w30 remained and as far as I am aware still does.
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The sticky thread at the top of the forum has a lot of oil info. Whether it's still valid I don't know as it's quite old now.
It seems an OK summary of the basics. The physics won't have changed.
Its unsurprisingly a bit contentious, (albeit unsupported received opinion stylee contentious) on the "thin v, thick" rabbit hole debate.
""The fact is that in the wrong application a high viscosity oil can be just as damaging as using a low viscosity oil."
However, it then goes on to say
"The use of an oil that?s too ?thin? can cause metal-to-metal contact, poor sealing and
increased oil consumption and conversely, an oil that?s too ?thick? can cause increased
friction, reduced energy efficiency, higher operating temperatures, and poor cold starts in cold temperatures."
The Metal-to-metal contact mentioned first for too thin is pretty much the gold standard definition of "damaging", with the increased oil consumption mentioned next potentially damaging your exhaust catalyst and coking up your rings, which could also be categorised as damaging
The downsides mentioned for thick oil are not really classifiable as damage, and will be to some extent self correcting, since as the oil gets hotter it'll get thinner.
So "just as damaging" seems quite a stretch.
That said, most punters running newish cars will be best served running the recommended skinny oils, but thicker oils might extend the engine life on older vehicles.
Edited by edlithgow on 02/11/2023 at 01:52
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I’ve bought some compatible Shell Helix 0w-20 which fits the Q5 so I’ll use that on the five year old Civic too which also takes 0w-20. Probably not strictly the right oil but surely it’ll be ok in a very small top up? Got some 0w-30 for the older A1 already which I gather is recommended so I’ll use that if needed. Thanks all.
Edited by RobertT on 02/11/2023 at 18:33
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I’ve bought some compatible Shell Helix 0w-20 which fits the Q5 so I’ll use that on the five year old Civic too which also takes 0w-20. Probably not strictly the right oil but surely it’ll be ok in a very small top up? Got some 0w-30 for the older A1 already which I gather is recommended so I’ll use that if needed. Thanks all.
You could probably get away with almost anything. There have been rare reported cases of engine failures due to mixing oils, but IIRC these were due to unexpected interactions between the Viscosity Index improvers at extreme low temperatures, causing the oil to gel, and they were probably mixing more than "top up" quantities.
On an old car, I used straight SAE40 for top up of a 15W40, (reasoning that it had no VI improvers to interact, and would tend to restore any viscosity loss due to shear). Might work as a "universal" top up?
Following a serious oil leak which took me a while to find and fix, this "evolved" into a roughly 50:50 mix, (probably roughly 20W40) which seemed to work quite well, clearing some varnish deposits, so I stuck with it for my next couple of oil changes.
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