Would you put this BACK into your engine?

[Brons2]

The flippant responses on this thread are really unnecessary. The BMW is a 2002, but people are talking like it's a 2012.

Dino 20w50 is all I ever used in my E30s. The used 5w50 should work fine.

 

[OVERKILL]

Originally Posted By: Brons2
The flippant responses on this thread are really unnecessary. The BMW is a 2002, but people are talking like it's a 2012.

Dino 20w50 is all I ever used in my E30s. The used 5w50 should work fine.


Hey, mine is a 2001! LOL!

 

[steve20]

Originally Posted By: NewYorkBuck
Honestly, it strikes me as a bit strange that someone who owns such cars would even consider such a move.

Porsche and BMW engines are extremely expensive. Motor oil is extremely cheap.

Proceed accordingly.....



And how do you think he got the money to own both, found it in a bag on the street?

 

[virginoil]

Originally Posted By: steve20
Originally Posted By: NewYorkBuck
Honestly, it strikes me as a bit strange that someone who owns such cars would even consider such a move.

Porsche and BMW engines are extremely expensive. Motor oil is extremely cheap.

Proceed accordingly.....



And how do you think he got the money to own both, found it in a bag on the street?


Still makes it a knucklehead idea IMO.

There are other ways of being frugal and shrewd with your money.

 

[electrolover]

Originally Posted By: HTSS_TR
Drain the oil from the Cayman into a clean container, use double coffee filter to catch any debris from the drained oil into another clean container before pour it into the BMW. The process of filtering is very slow, it may take more than 1 hour per quart.


thats awesome!! thats what im going to do with my 40 gallons of 3k oci oil and put in bottles for 1.50 a qt

 

[LineArrayNut]

If its still clean, ie, not dark, why the heck not? Or you could send it to me for disposal... ;-)

 

[A_Harman]

Originally Posted By: Matt_N
Ok -- new question

Do we know with some certainty what happens to either visc @ 40C or viscosity index (VI) as an oil is used?

For instance, in general, we know that visc @ 100C decreases as an oil is used (assuming no contamination or long OCI, etc). Does the same hold true for visc @ 40C? Does VI stay the same as an oil is used, since it is a proportional measure of visc at 40C and 100C??

The biggest question I'm now trying to answer is whether the used 5w50 oil will be too thick for winter service (temps down to 0F). If I can convince myself with data that it won't be too thick to try it, then I'll do the experiment and report back.

Thanks
Mat


Since this thread got bumped back to the top, I reread it and saw that this question wasn't addressed. In a 5w50 oil, there are going to be a relatively large amount of VII's, which will shear at high temperatures. As a result, the 100C viscosity will decrease, as will the Viscosity index. The 40C viscosity will not change very much.

 

[teddyboy]

Whether to put used oil in a BMW? Now there's a question you don't see everyday! Issues related to the effect on your BMW engine aside, why in the world would you want to go to this much trouble when M1 0W40 sells for around $6.50 per quart at Wally World all the time and on sale at O'Reilly for $4.99?

 

[berniedd]

I don\t like waste, and if I were in your situation, I would reuse that oil. I'd filter it first though, using my home made gravity fed filter using several layers of tissue paper (aka bypass oil filter). It will take 5 days or so.

 

[CATERHAM]

Originally Posted By: A_Harman
Originally Posted By: Matt_N
Ok -- new question

Do we know with some certainty what happens to either visc @ 40C or viscosity index (VI) as an oil is used?

For instance, in general, we know that visc @ 100C decreases as an oil is used (assuming no contamination or long OCI, etc). Does the same hold true for visc @ 40C? Does VI stay the same as an oil is used, since it is a proportional measure of visc at 40C and 100C??

The biggest question I'm now trying to answer is whether the used 5w50 oil will be too thick for winter service (temps down to 0F). If I can convince myself with data that it won't be too thick to try it, then I'll do the experiment and report back.

Thanks
Mat


Since this thread got bumped back to the top, I reread it and saw that this question wasn't addressed. In a 5w50 oil, there are going to be a relatively large amount of VII's, which will shear at high temperatures. As a result, the 100C viscosity will decrease, as will the Viscosity index. The 40C viscosity will not change very much.

It's true that when an oil shears, particularly the 5W-50 grade which is notorious for shearing a lot, there will be a drop in the oil's VI. But the oil's KV40 will drop, although not as much as the KV100. If the KV40 didn't drop the oil would become noticeably thicker on start-up as the oil shears and that doesn't happen.

 

[Malo83]

Originally Posted By: berniedd
I don\t like waste, and if I were in your situation, I would reuse that oil. I'd filter it first though, using my home made gravity fed filter using several layers of tissue paper (aka bypass oil filter). It will take 5 days or so.


Surely you jest !!!

 

[Trajan]

Putting used oil in an engine is like bathing in used bath water.

 

[Matt_N]

UPDATE

Thanks for all of the interesting feedback. You guys need to relax; the BMW cost me $4,500 last winter. If my 2.5L blows up, that means I get to put a 3.0L M54 in it

At any rate, I drained the Mobil 5w50 from the Porsche and sent in a sample. Unfortunately, I was in a hurry and didn't have a clean container into which I could drain the oil -- so this used oil could NOT be reused in the BMW. Just the same, below is a link to the UOA.

If you ask me...with a TBN of 8.7 and kV @ 100C = 14.41 cSt...I think this oil is JUST RIGHT for the M54 BMW motor in the warmer months!!!

Mobil "2" -- 5w50 UOA

Matt

 

[LineArrayNut]

soooo... did you?

 

[r34dy2fly]

He just said no....

 

[LineArrayNut]

just because of the dirty oil pan; I was curious if further efforts proved fruitful...

 

[MrWideTires]

I do it all the time, run Rotella T6 in my SpecV to about 3000 miles, then use it on the work truck for another 7000 miles... and THEN it goes into the lawnmower.

 

[djb]

Originally Posted By: BMWTurboDzl
The oil does not have LL01 correct? It very well may cause problems with the VANOS and I would not rely on the viscosity of a cheap UOA as a basis for your decision.


I know this thread is from ancient times, but I felt the need to comment.

There isn't something magically demanding about VANOS. It's the least demanding oil user in the engine. It's just a solenoid valve hydraulic actuator. A pretty big one. There are no small passages or hot spots. Full pressure oil goes through a spool valve and is let into a big cylinder where it pushes on a piston. The oil from the low pressure side drains through the head, where it mixes with the oil that just did the difficult task of lubricating the cam and lifters.

 

[Cristobal]

I agree with the guys who say drain it carefully and filter it, so it will have no solid particulate matter of substantial size, and make sure that it does not get accidentally contaminated. If the oil analysis says OK, it is OK - In theory, but keeping contaminants out is the tricky part, as you know.