Mixing oils?

[Bruce Page]

Does it matter? I serviced my air compressor yesterday and accidently mixed synthetic compressor oil with non-synthetic. Probably less than a quart total at a ~ 40/60 ratio.

[Jim Becker]

I don't know the "correct" answer to the question, but I suspect there will be no issue...

[Mikail Khan]

Can't recall seeing any synthetics that were not compatible with mineral oils.

Synthetic oil datasheet should have info.

MK

[Kevin Beitz]

I will jell up when mixed...

[Bruce Page]

I will jell up when mixed...

Well, that's not good. I will drain it and refill.

[Wayne Lomman]

Don't do it! We have huge labels on our shop compressors warning against this. The damage can be terminal. Cheers

[Mike Cutler]

If the compressor is spec'd for synthetic, and you put in 'dino oil, it's a problem. If the compressor oil specs are for 'dino oil and you add synthetic, that's not that big of an issue.
40/60 is kind of a big ratio. I personally would change it. I've not heard of mixing the two and having it "jell", but you never know.
I think changing it to one or the other will give you peace of mind though. Oil is "cheap".

[Curt Harms]

^^^^^^ likes this ^^^^^ Probably no problem at least short term but why take the chance?

[Joe Spear]

I don't know if it makes a difference with compressor oil, but I did some research for automobile oil. My mechanic said that I couldn't change to synthetic oil if I had been using anything else. But when I looked into it, different researchers and oil companies said there would be no problem. In fact, synthetic-blend oil, which is an option for most cars, is just a mixture of mineral oil and synthetic oil. I did change to full synthetic for the past three oil changes with no problem whatsoever. Check with your compressor manufacturer. They should know if the mixture is all right or not.