Safe to switch? 10w-60 to 0w-20 BMW M50tu

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Currently running 10w-60, still burning oil pretty fast. Want to try Amtecol 9000N 0w-20. My gearing is fairly short so I'm turning almost 4k rpm on the highway, barely getting 21mpg, curious to see how much 0w-20 will help. Was also thinking, if the rings are worn, shouldn't a thinner oil be easier for the oil rings to wipe off the bore?

Most make pretty good arguments against using thin oils in motors not made for them, but I still want to hear what others think. I read something a while ago, that the bearings fill with oil, and because they're spinning so fast and oil is constantly being replenished, it's capable of sustaining much higher pressures. So thin or thick oil should be fine.

Worst case, I destroy my engine, m50's are everywhere for cheap, still hoping it doesn't happen haha
 
Here's the important question: Do you genuinely want to improve the situation (burning/usage), or just desire to fool around with different oils?
 
Originally Posted By: thehomelessone
Currently running 10w-60, still burning oil pretty fast.

...........

curious to see how much 0w-20 will help





What?
crazy2.gif
 
That's a HUGE leap in viscosity. If your motor's bearing tolerances are designed for 10w-60 and you use 0w-20... I'm expecting that you'll lose a lot of oil pressure
 
Originally Posted By: SnowDrifter
That's a HUGE leap in viscosity. If your motor's bearing tolerances are designed for 10w-60 and you use 0w-20... I'm expecting that you'll lose a lot of oil pressure


Given that he's talking about a "M50tu", one can infer he has an early '90's E34/E36.

Here's the breakdown:

-4 To 50 F......10W-30
-4 To 68 F......10W-40
Above 5 F......15W-40
Below 32 F......5W-20
Below 50 F......5W-30
 
Lol thanks for your responses guys, just needed the attention, /thread.

Seriously though, what about oil film shear strength? Some 20wt oils did very well on this list:
http://540ratblog.wordpress.com/2013/06/20/motor-oil-wear-test-ranking/

I'll hook up a oil pressure gauge next time I'm at the shop. Wouldn't the thinner oil be easier for the oil rings to wipe off? Wouldn't I also be burning less oil since there won't be as much left on the bores? Seems like the only issue is having enough oil pressure.

Did a swap in an e30, using g240 trans and 4.27 diff. Stock gearing as m42 e30 convertible. Folks behind me on a hard 120 mile drive said they didn't see any smoke from the tailpipe when I asked them to keep an eye out. Get a puff of blue smoke when I take off from a long idle, so valve seals I guess.
 
1) Flow <> lubrication
2) Positive displacement pumps mean that there's not more flow
3) Pressure <> lubrication
4) Oil film thickness is geometry (which you aren't changing) speed (which you aren't changing), and viscosity (which you are...thinner oil, thinner film)
5) The Rat tests have been discredited for relevance in engines.
6) Thinner oil reduces consumption - novel idea, flies in the face of science.

But your engine, your car, your experiment, and as you say, the engines are widely available and cheap.

Personally I don't think you'll blow it up (if you do, please start a pile, it will help BITOG later if there's a pile of failed engines, even one).

If you do do it, run your OCI, and please post an oil analysis. I'd be particularly interested in the bearing wear parameters.
 
Originally Posted By: thehomelessone
Currently running 10w-60, still burning oil pretty fast. Want to try Amtecol 9000N 0w-20. My gearing is fairly short so I'm turning almost 4k rpm on the highway, barely getting 21mpg, curious to see how much 0w-20 will help. Was also thinking, if the rings are worn, shouldn't a thinner oil be easier for the oil rings to wipe off the bore?

Most make pretty good arguments against using thin oils in motors not made for them, but I still want to hear what others think. I read something a while ago, that the bearings fill with oil, and because they're spinning so fast and oil is constantly being replenished, it's capable of sustaining much higher pressures. So thin or thick oil should be fine.

Worst case, I destroy my engine, m50's are everywhere for cheap, still hoping it doesn't happen haha


My first reaction is either trolling here or this proposal is nuts ?

Either way go for it you reckon M50's are cheap.
 
Jethus, well seems like it's guaranteed my motor will seize, I'll try 0w30 for the winter. Going to rebuild another m50tu for boost, will try 0w20 in the old motor then, thanks.
 
Originally Posted By: 901Memphis
I would use Mobil 1 0W40 European Formula first and see how it goes.


So would I!
 
Originally Posted By: thehomelessone
Jethus, well seems like it's guaranteed my motor will seize, I'll try 0w30 for the winter. Going to rebuild another m50tu for boost, will try 0w20 in the old motor then, thanks.

No you're engine won't seize. I've run M1 0W-20 in my M50 engine in the winter in years past and if your engine bearings are in good shape you should be able to maintain the minimum test spec' oil pressure if your oil temp's don't get over 85-90C.

But from the sounds of things if you're burning that much oil you're engine is likely knackered and you won't be able to maintain adequate OP once you've got the oil up to low normal operating temp's. And I suspect the 20 grade oil will be consumed at an even faster rate.
 
Originally Posted By: A_Harman
Here's a wild idea: run what the manufacturer recommends.


You're living on the edge there A_Harman. I don't know if we're ready for that yet...
wink.gif
 
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