Anyone else switch to thinner oil during winter seasons?

[Rick L]

Anyone else switch to thinner oil during winter seasons? I use 0w-40 during spring, summer, and fall and switch to 5w-30 during winter. Recently, I switched to 0w-30 (new Mobil 1 that’s out). Or do you stick with same weight year round?

[Jehu]

Just added Royal Purple 5w30 to the 540..

[Torque]

I used to run 20w50 in the summer and 10w40 winter in the 535i; didn't have any issues even the few days we had 0 degree temps last winter.

[BMW4LIFE]

I have been running 10-40 high miles Mobile 1 for some time now in all 4 seasons and everything is awesome here

i want to run the 0-40 but i have a small leak and am afraid that it will become worse with the thinner oil =/

still curious about the performance difference when it comes to lubricating the engine in these cold starts...then again i live in ca so it doesnt get that cold...around 39 F at the worst in my area

[Bo525i]

I run 5-50 year round here in scandinavia!

[Rick L]

Correct me if wrong but doesn't "W" in 0w-40 means "winter" grade? And actual weight of the oil for 0w-40 is 40. "0w" means it can flow at that specification. I have always used lower weight 30 or *w-30 in winters and *w-40 for all other seaons.

Also, just wondering how many members here are using "High Mileage Oil"? I have mixed feelings about using this. I afraid it might have adverse effect.

[Ferret]

Isn't 0w and 5w the same actual weight?

I seem to remember reading somewhere that 0w is actually 5w with a better temperature range.

"w" means weight, surely?

We're having fun with the temperatures here at the moment, had to actually put the 8 away for the week because the roads are like oiled glass at the moment!

[ArnZ!]

Just so you guys know the first number is the weight of the oil at 40 degrees Celsius. The second number is the weight of the oil at operating temp, 100 degrees Celsius.
Just think of the numbers as "oil thickness at startup and oil thickness at operating temp."

So a 20w50 will be thicker at start up then a 10w50 would but when they both get upto operating temp they are both the same. Same with 0w40 and 10w40 and so on.

The real measurement of the oil weight is in Centistokes. So for example, the oil i use in my car is a 10w50 and its really a 131 cSt when cold and 18.8 cSt when at operating temp. The old oil i used was a 20w60. Which was 24 cSt when cold and 24.4 cSt when at operating temp.

The SAE grade of oil is more of a rough indication of what weight in cSt the oil is. So an Xw50 oil weight at operating temp is roughly somewhere between 15 cSt and 19 cSt. A Xw30 oil weight will be somewhere between 10 cSt and 12 cSt and so on. These are just figures off the top of my head.

So when choosing an oil you would want something thats thin and startup and thick enough at operating temp.

[Tiger]

Geez... are you all that far behind in oil technology? Sounds like granpa's rule of thumb.

0W is thinner than 5W... so how is 5W thinner than 0W? It is not.

30, 40 and 50 or even 60... thicker is better? Not really. We don't run our engine 100% racing duty cycle.

Which offer better protection from wear and tear? 50? Nope... 30 does.

Which gives better fuel mileage? 0W30 or 10W40... at least most of you will get this right... 0W30.

Which offer more protection at high RPM? 5W30 synthetic or 20W50 dino? Synthetic wins. How about this one... 5W30 synthetic vs 20W50 synthetic? Thinner wins...

There are lots to learn and it pays for you to read up on facts about oil...

[Rick L]

Thanks for clarifying this guys. I was told by many to use thinner oil, both cold and operating temp, for winter if your climate deeps below freezing point. Or have I just switched all this time that had no effect either way? But maybe it's just in my head but I do think my engine runs better with thinner oil during cold winters.

And I'm stuck using 10w-60 for my M3 regardless of climate condition... So called only recommended fluid by BMW, Castrol TWS 10w-60.