Proper Oil weight for '91 BMW E30

[Z Licious]

I have a '91 BMW 325i (E30) with the 2.5L straight six. My owners manual calls for 20w-50 in anything above like 0 degrees F. With the move to thinner oils and 20w-50 getting harder to find, can I use a thinner oil in this engine?

The BMW guys say you need to use 20w-50 because the engine oil passages and pump were designed for the thicker oil and using a thinner oil will not allow for proper oil pressure.

What do you think?

 

[nel]

I recently bought a '90 325is, and the previous owner used Valvoline 10W30. Analysis on that oil after 3K miles actually looked pretty good (UOA) , and I can't see any undue deposits through the oil filler hole.

I suspect that using a lighter viscosity than 20W50 with today's better oils isn't a problem like it would have been back in the '80s when this engine was introduced. Having said this, I like using 15W40 in that engine. Given where you're located, and if you're planning on driving during the winter, I'd suggest you try a synthetic 5W40 (Rotella T, Mobil 1 Truck & SUV, etc.)

 

[Thatwouldbegreat]

I've had good luck with Redline 10W-40 in an 86 325es.

The original engine is in great shape at 400K.

I ran this car since new on Castrol GTX 20W-50 summer and 10W-30 winter , and changed oil every 3K.

Then I switched to Mobil 1 15W-50 every 5K.

But the car runs much better on Redline 10W-40 every 7K.

One highly knowledgeable oil guy said to go with SAE 0w-30/0w-40 winter and 15w-50/20w-50 summer.

5W-40 synthetic was a 'year round' compromise, but not ideal.

If I ever change from Redline 10W-40, I may go with:

Redline 5W-30 winter / 10W-40 summer or 5W-40 year round

----------

Other contenders:

-Mobil 1 0W-40 winter,

-Mobil 1 Extended Performance 10W-40 summer,

-Mobil 5W-40 Truck & SUV [Delvac 1 ] year round,

-Amsoil 5W-40 European Formula year round,

-Amsoil Series 2000 0W-30 winter,

-Amsoil AMO 10W-40 summer

-Maybe the German Castrol European Formula 0W-30 winter or maybe year round.

---===---

If you want to run dino oil; then I'd still stick with 3000 mile oil changes and use 20W-50 summer and 10W-40 or 10W-30 winter.

[ September 15, 2005, 07:34 PM: Message edited by: Thatwouldbegreat ]

 

[JHZR2]

my 91 318i (M42 4-cyl) does GREAT on rotella 5w-40. Others I know from the roadfly boards are having good luck using it in their 325 cars.

Another good option for the 325 has historically been chevron delo 400 15w-40. With its new dose of moly, its even better!

Ive tried M1 0w-40 in this engine in the cold of winter, and didnt like the results... UOA confirmed this.

consider a synthetic (amsoil) 15w-40 as well, as it would be a good choice.

Id go with the rotella syn 5w-40 though, as its such a great deal at wal-mart!

JMH

 

[Thatwouldbegreat]

Let me change my post:

Scratch Mobil 1 0W-40

Add Rotella 5W-40

Add Delo 400 15W-40

Add Amsoil 15W-40

Thanks JHZR2 !

[ September 15, 2005, 11:14 PM: Message edited by: Thatwouldbegreat ]

 

[joatmon]

My wife's old 86 528e was sold a couple of years ago at 197k. I put Mobil 1, 0W30, 5W30 and 10W30 in it. At the end, I used Schaeffer's #703, 10W30. Most changes were at 5k. The engine never used any oil, at least not enough to tell. It ran super and was still getting 26 or 27 MPG around town. Kinda wish I had it know with gas prices where they are.

I know I'm in the minority here, but I'll let this experience speak for itself.

Oh, if the engine hasn't been well maintained, or is having some problems, the heavier oil makes sense to me.

Good luck,

Jack

 

[JHZR2]

joatmon,

very interesting results... BMW engines are good engine, and unles something is really messed up, you udually dont see big drops in compression pressure, etc., so regardless of the realized wear rates that super-thin M1 gave - you did really well. This speaks volumes to the sage advice of the necessity to just do PM regularly, regardless of even what is used!

That said, there is something to consider w.r.t. the owner's manual... 40 weight is more or less the minimum they suggest... Modern 40wt oils are so good though, that its probably the best one to pick.

IMO...

JMH

 

[Z Licious]

Thanks for all the help. I will probably end up going with Delo or Rotella. I am trying to stick with something that is readily available in my area. Everything is either 20W or 30W now and 40W and 50W are all but dissapearing it seems.

I will probably just run 15W-40 in the spring through summer and then 5W-30 or 5W-40 (if I can find it) in the winter.

Thanks

 

[JHZR2]

Up in boise, id go with 5w-40 year round and not think twice... ID is beautiful and the temperature is always right (cold or teperate... beautiful).

Go with the rotella 5w-40 - easiy found at wal-mart.

JMH