1985 BMW 318i with M42 engine swap - oil suggest?

[irish44j]

I just swapped an M42 engine (from a later 318is) into my old 318i (used to have an M10).

Engine has been heavily refreshed but didn't rebuild, and using original pistons/valves, etc.

Mileage unknown, but compression is within factory spec.

Car is used primarily for rallycross from March to November, but also driven to events (about 70 miles highway) and driven on weekends for fun. I drive it hard. Almost always. This car isn't for leisurely cruising

I'm near Washington DC, but car is driven in the hot summer and cold winter here and there. Don't mind using different viscosities/oil seasonally though....

For my WRX I use Rotella T5 and/or T6 (depending on what's on sale), which I can get at wally-world of course.

Any suggestions on the best oil for the M42 in the BMW?

 

[Seventh]

Do you have an oil pressure gauge?

I ask because I've seen a few 44 engines that would get some oil light flickering action in hot weather traffic while running a 30wt oil. I've also seen them go 300k mi on a strict diet of 20w-50 conventional... but sounding like a diesel.

Considering how you drive the car, I'd be inclined to recommend just using the T6 for simplicity's sake since you're already using it. Watch consumption and pressure if you can, and do a UOA or two to see if things look ok. I can't imagine they won't.

 

[JHZR2]

Rotella 5w40 is a great choice and Ive used it for years in my M42 in my 1991.

M1 HM 10w-40 is also a robust ACEA A3 oil that you might consider.

 

[irish44j]

Thanks. Seventh - it will have an oil pressure gauge once I'm done with this swap and actually driving the car again.

Since I don't put many miles on the car so my OCI is pretty long, sounds like T6 will be the way to go, else t5. Thanks.

 

[JHZR2]

I wouldnt run T5 in it. IMO 30wt is a bit too light for the engine.

There was a time when MB for example would spec the HD or more robust version of the oils and only allow the lighter variant for really low temperatures, when the oils were low viscosity (like a 30wt).

In older manuals, 30wt is only allowable at really cold temps, in newer ones, 30wt was allowed only at really low temperatures, unless it was what is now the precusror to ACEA A3.

So if the HTHS of T5 is high enough to qualify for ACEA A3, you might consider using it... But Im not sure it would meet this.

Your selection aligns to this:

SPecial oils are in my interpretation, wider viscosity synthetics, but the basic premise of 40 or 50wt still stands.

 

[dparm]

I would run any quality 5w40 and call it a day. T6 is a good value oil, as are pretty much any of the other 5w40 HDEOs.

 

[fdcg27]

Mine seems to do very well with Maxlife 10W-40.
Either the green or the red bottle would be appropriate.
I had a very good UOA using Maxlife Nextgen 10W-40 for 4K last summer.

 

[KCJeep]

The Rotella 30 wts have an HTHS of 3.5, on the thick side for 30's and right at the level recommended for many German cars, but I wouldn't run a generic PCMO 30 in it the HTHS would be 3.0-3.1 for most of them.

 

[Seventh]

Originally Posted By: KCJeep
The Rotella 30 wts have an HTHS of 3.5, on the thick side for 30's and right at the level recommended for many German cars, but I wouldn't run a generic PCMO 30 in it the HTHS would be 3.0-3.1 for most of them.


T5 is a great oil, and I completely agree with this statement, however the oil light flickering I spoke about was on M42/44 cars running the BMW synthetic, which is also 3.5 HTHS.

He will be better informed with pressure and temp gauges, but I still wouldn't run any 30wt oil in that car during warmer months if it's getting thrashed like the he suggests. $.02

 

[OVERKILL]

M1 0w40 or D1 5w40 would be good choices as well here.