Oil for older high mileage BMW's

[Local Color]

I have several BMW from the mid 80's. M30's, M105 turbos. What would be the recommended oil for this old iron. Both cars are low 100k mileage.

Im in Texas where it really never gets cold. I have been using Castrol for sever years. Seems ok although there seems to be more lacquer than I would like - Cars do not use oil. Using 20-50 for most of the year. No tick tick.

 

[edyvw]

I would go with 10W40 Synthetic. Maybe Castrol 10W40 SPT.

 

[dparm]

Mobil 1 High Mileage 10w40 is worth considering, but I don't think 100k is really "high mileage". If you said 250k+, then I would agree.

Truthfully you could probably run any off-the-shelf 5w40 or 0w40 with good results.

 

[SteveSRT8]

Originally Posted By: dparm
Mobil 1 High Mileage 10w40 is worth considering, but I don't think 100k is really "high mileage". If you said 250k+, then I would agree.

Truthfully you could probably run any off-the-shelf 5w40 or 0w40 with good results.


Agreed here as well. 100k miles is just about when I know whether or not a car is any good, it's also a great time to decide if it is a 'keeper'.

Most vehicles these days make 100k easy...

 

[CATERHAM]

I would discontinue using a 20W-50 in any older engine in good condition.
You may find it interesting that Porsche has back spec'd M1 0W-40 at least 30 years for their cars that used to be spec'd for 20W-50.
I'd recommend nothing heavier than M1 0W-40 for 80's era BMWs.
BMW's own 5W-30 would also be a good choice. Ultimately if any of these older cars have oil gauges, particularly an oil pressure gauge then a more precise viscosity choice can be made.

 

[285south]

I too agree on discontinuing the 20w50 and go with Mobil 1 10w-40 High Mileage. Would have suggested Schaeffer's 9000 5W-40 since it has the highest MolyB compared to the others but saw your location.

 

[Nickdfresh]

I agree with the Mobil 1 10W-40 HM recommendations. You could even use M1 HM 10W-30 as it also meets the ACEA A3 spec. So does Valvoline MaxLife Synthetic 10W-30.

I'd consider Mobil 1 0W-40 or Castrol's Euro 0W-30 A3/A4 or 0W-40 also...

 

[Local Color]

all good information - if I do go all sync - is there a pre-tretment I should do (this would go for all the functions ATF, Rear end...) for all sync fluids.

 

[Shannow]

There's no absolute reason to go for synthetic in texas if you've been running dino for hundreds of thousands of miles, going to a dino/GrII+ 15W-40 is no biggie.

If you really feel that you need to go synthetic, a quickie change with a dino may be worthwhile, as any residual in the engine will then be "clean"(ish) rather than dirty.

As to synthetic, if following Porsches advice for your BMW engine, they haven't back-specced M1 0W-40 for the engines, they fill new ones with M1 0W-40, and have an approved list of 0W-40, 5W-40, and 5W-50s, ranging from GrIII to what was formerly called synthetic.

http://www.pedrosgarage.com/Site_3/Porsche-Approved_Oils.html

Any of them are pretty decent.

 

[fdcg27]

You probably don't need a 20W-50 although that's what your OMs will recommend for warmer weather. All of the Germans recommended this grade at the time. Probably not needed or really helpful even then, certainly not needed now.
100Kish on on 'eighties car cannot be considered high mileage, either.
If your photo is representative, you have some nicely preserved survivors.
I'd usually recommend the Maxlife 10W-40 that I use, but for these nicely kept old turbos, I'd probably spring for M1 0W-40.