It's quite common in the motorcycle world: for example, Suzuki specifically state in the service intervals for most of its motorbikes that the oil filter is changed every 2nd oil change (apart from the first change, which is done at 1,500 miles from new). I follow this recommendation on my SV650, which now has 66,000 miles up and runs like a Swiss watch.

As you point out, there are variables at play. The oil filter for Suzuki motorbikes is common across much of the range and is a large car-style screw-on canister with a high filtration capacity: the same unit is used on the 1,340cc, 190bhp Hayabusa so it's obviously more than enough for my 650cc V-twin. Also, my bike only has 2.5 litres of oil in its sump, compared to 4+ litres in larger bikes, so I'm quite happy that the oil filter has the filtration capability to last two oil changes.

Not often we see eye to eye over oil changes John F, but yes i change the filter every time too.

Having seen some of the filters cut open and the gunge therein on youtube where engines have seen service neglect for 20k+ miles, that filter is an engine life saver.

If cost is an issue, do what i do, buy half a dozen of the things when there's an offer, typiucally my filters have cost around £6 (Subaru) and £8 (Toyota, 3 times the size) each buying them when on offer, when compared with the cost of another, even used if you can find one, engine fitted why would one take the risk.

Again if cost is an issue, spend out on a 20 litre drum of the correct oil when you see it at the right price, i've been doing that for decades and don't consider myself broke just yet:-)

One of my mentors back in the 60's used to change the filter alone between oil changes on his old Austin A40, dare say that was a filter element rather than a spin on jobbie so would have cost pennies, personally i've never done that and its a new filter every time.

One other thing, not all filters are the same, i don't buy main dealer filters necessarily but instead buy what are hopefully decent quality aftermarket, i was using Wix on the Toyota at one time and noticed on a cold start it took about a second for the oil light to extinguish, since changing to Hengst the oil light goes out instantly, i put that down to a better anti drain valve as the filters are upside down on that car, but happy for any other suggestions.

I had a Saab 9-5 Aero for 11 years, and knowing about the engine's propensity for sludge build-up in the sump, I changed the oil and filter every 6000 miles. Sometimes that was three times a year, but it seemed false economy not to change the filter every time. I also bulk bought the filters to reduce the cost. At 235,000 miles, when we sold it, it still ran sweet as a nut on the original turbo, timing chain etc. Must have done something right!

I guess on a lower performance engine doing fewer, and less hard, miles changing the filter every other oil change might work, but tbh given the comparative cost of a filter vs. a new engine, I personally wouldn't take the chance.

My habit has always been every other change for petrol engines, every time for a diesel, which produces more undesirable combustion products. Also not to stretch the change interval too far - especially as most car makers already do that.

Think I've heard every second oil change is/was a recommenfation from Toyota, though I've never had a Toyota so cant confirm.

This may not just be/have been a cost cutting measure, since filter performance (initially rather poor, as in coa***, on a standard full-flow filter), improves significantly as the filter gets loaded with particulates, so you might get better overall filtration over the two oil changes)

It wouldnt be VERY technically demanding to measure the pressure differential across an oil filter (either in the car, or on the bench) which would tell you how clogged it was, though you would need some plumbing and guages.

I would also think it should be possible to backflush a clogged filter and return it to service. I've done this with fuel filters that I couldn't immediately get a replacement for, back flushing alcohol through them with a syringe until rust stopped coming out and it seemed to work fine, though of course it would be messier with an oil filter and I would probably use a different less hands on technique to minimise my exposure to carcinogens.

On the flip side, it might be possible to pre load a standard, coa*** full-flow filter with additional media to improve its performance. The very fine lint that settles out after washing clothes in a bucket looks like potential supplementary filtration medium to me

But as you say, though, they arent expensive enough, to justfy the trouble.

I doubt they are as vital as seems to be the recieved opinion here either. The standard full flow filter lets a lot through, and many engines (VW aircooled, and most motorcycle and scooters, for example) dont use them at all

Edited by edlithgow on 19/12/2024 at 22:52