Can I mix motor oils?
 

I have been using Valvoline Max Life 20W-50 in my 93' 300E 3.2L engine.
I change the oil every 2,500-3,000 miles. Can I mix this oil with another brand, such as Castrol 20W-50 Synthetic Blend? OR any oil for that matter.....IS IT SAFE TO MIX OILS if they are the same SAE - 20W50?

What are your thoughts on synthetic blends?
Thanks!!:confused:

You can mix motor oils without any problem.
Synthetic oils will mix with mineral oils (and vice-versa) and all grades will mix with any other grade.
Synthetic oils: Do a seach on ENGINE OILS"
You'll have enough reading material for the next 48 hours.
jackD

Ditto - unlike gasolines (which can do various weird things when mixed), most all motor oils can mix (without problems) with any other motor oil. (Of course, we are talking normally available dino or synthetic 4 stroke oils).

In fact, if you analyze a bottle of Mobil1, you will be surprised at how many different oils are mixed in there.... (And, you will be surprised at how many of them are NOT synthetic, although some are....)

-DavidL

DaveL: You said:
"Ditto - unlike gasolines (which can do various weird things when mixed), "
What do you mean????
I've been in oil refining/maketing for over 25 years and this is the fist time I read such a comment.
Jack

Maybe he was referring to mixing bleach and ammonia. ;)

Duke

My experience with this is from the practical side, and is specific to experiences I have had (and discussed with others) mixing race fuels and "pump" gas.

The pump gas that we normally used had MTBE or other oxygenating additives, so this might have led to it.

I have seen very unusual plug chops (run engine wide open, top speed, for 1 minute, turn off and coast to stop, pull spark plug and (hope) to determine jetting conditions) when using a mix of pump gas and race fuels such as Trick, Sunoco 108 unleaded race, and others (which I imagine are mostly the same stuff with different labels). We saw what appeared to be debris, which was actually congealed and burnt stuff(?) that was sticking to the spark plug (all over, but certainly not evenly distributed).

A rep from Sunoco claimed that certain pump gas additives caused the race fuel additives to fall out of solution. I haven't heard this exact explanation elsewhere...

As for mixing pump gas (91 with 89 or 87), I don't think there is any problem with this - most pump gas is the same with more or less additives depending upon which brand or which grade you end up with.

-DavidL
92 500sel
82 QPort
93 ZX11
86 535i