I believe this topic has been on here before and have browsed through past postings but they dont seem to quite answer my query.
I drive a Saab 9000 Aero, 2.3l Turbo, so the engine and turbo can get pretty hot.
It has been run on semi-synthetic before I bought it with regular changes, but I want to try it on the best oil I can get, and am hence contemplating Mobil 1 with 6-monthly changes (approx 5l miles).
The cost doesnt bother me too much.
What I have heard are rumours that it is too thin, and doesnt provide the turbo shaft with a sufficient cushion of oil on startup.
As it is recommended for high performance/turbocharged engines, this seems strange.
Will putting in the most expensive oil damage my car, or will it live happily ever after?
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Gavin
I have no experience with this oil, but I did own a nissan 200 turbo, and used fully synthetic oil in it once. The problem I found was that the oil was too thin, and although it didn't seem to harm the turbo, it did breach the seals in the turbo and cause some blue smoke. This is unlikely to harm the engine (if its not catted), but it does put off prospective purchasers. My understanding is that it is best to get a mid range oil (viscosity that is) which will coat the bearings when starting up, and wil flow enough to prevent carbonisation when hot.
I went back to semi synthetic after that. I know that other people on here don't recommend a fully syn oil if the car is older and is used to semi oil as it can dislodge sludge, which can block oil feed pipes and starve the turbo of oil (which is precisely what you want to avoid).
I hope this helps.
Regards
Jonathan
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The engine should be sludge free as it has had engine flushes when the oil was changed before, and the car isnt that old - 97.
Was the breaching seals problem when the oil was first released and didnt have special seal addiditives?
Not that I condone the killing of seals by oil manufacturers.
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Mobil makes other grades of Mobil 1, so though the normal Mobil 1 is 0w/40, you can get 10w/40. I think this is the grade used by Lotus for the Esprit factory fill.
HJ
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Having mailed Giles Fairweather at Abbott Racing (Saab tuning specialists) he uses Mobil 1 10W40, but buying direct from Mobil as it doesnt seem to be available to the general public.
Again, the necessity for frequent oil changes above all else is stated. so I intend to find myself a 5 or 10 W 40 fully synthetic for now and leave Mobil 1 until next time.
Many thanks for the help from everyone who replied.
mail from Abbott racing below for reference:
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Dear Gavin
Many thanks for your E-mail.
We recommend and use Mobil Motorsport, which is a 10/40, we buy direct from Mobil and I do not know how easy this oil is to get off the street.
On a personal point of view, I would change oil in every car in every situation, every 6000 miles. Having seen engines, customers and different situations for the past 20 years, regular oil changes, even if the oil
is cheaper, keeps the engine clean and in efficient working order.
We have seen cars that have done 35000 miles with no oil changes, that the engines are destroyed. and we have seen cars with 250,000 miles on them that have regular 3-6000 mile oil changes and the engine is still like new, speaks for itself.
Try to avoid 0 viscocity as if your car has a tendancy to have a slight oil weep, this oil will find it, it also does not help with tappets.
You don't necessarily have to go Mobil 1 any fully synthetic engine oil changed regularly will work very well.
I hope this helps.
Kind regards
Giles Fairweather
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Gavin
The benefit of the high tech synthetics is that they can be thin when cold, and therefore quickly provide lubrication, but also provide lubrication when hot.
Although the oil is a 0-40 or whatever, it doesn't mean it gets thicker when hot! All oils thin out. A 0-40 for example is as thin as a '0' when cold, but thins out no more than a 40 when hot. So, it provides the cold start performance of '0' and the hot protection of a '40'. So, no risk to the turbo bearings on start up. It won't be 'too thin'
Check the handbook, and make sure that the 'hot' viscosity of the chosen oil is at least what Saab recommend.
Check also the service rating of the oil. Most, if not all, semi and full synthetics are going to be the latest ACEA A3 spec., which is what a turbo engine really needs. That's at least as important, if not more so, than the SAE rating.
Whether a full syth oil is worth the extra cost with 5k oil changes is another matter. Many on this site reckon it isn't, and would use a semi-synth. as you are already doing.
Regards
John
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If you are interested go to www.superblackbird.co.uk/ and click on the Blackbird forum (1/2 way down on the left) then go to page 8, its at the bottom, for my slagging off for using full synth in my Blackbird. An 1137 cc engine producing about 165 BHP. It gives the bikers view on the same subject.
Bill
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