quick question: on mixing synthetics and non-synthetics

quick question: on mixing synthetics and non-synthetics

Correct me if I'm wrong, but nothing harmful will come of mixing synthetic motor oil and conventional motor oil.

Is it the same of synthetic brake fluid and conventional brake fluid? Can I mix synthetic with non-synthetic? Or should I just stick with conventional until I have the time to flush it out and refill with synthetic?

there's no point in putting in synthetic if you have mineral oil already in there..

it's like mixing premium with regular unleaded

You are correct that most conventionals and synthetics for motor oil an brake fluid are completely miscible. That is, they will mix together. Nothing "harmful" will come from the mixing of the two as long they have similar bases.

Eg. Almost all synthetic motor oils use some convential basestock in them to keep the oil additives in suspension. Brake fluids are slightly different. DOT 3 and DOT 4 will mix with each other but DOT 5 will not mix. DOT 3 and DOT 4 are polyglycol based and DOT 5 is silicone based. Polyglycol will eat paint and is highly hygroscopic (absorbs moisture) - but has a very stable compressibility for different temperatures. Silicone will not eat paint and does not absorb moisture - but has a variable compressibility for different temperatures.

There are new DOT 5.1 that can mix with DOT 3 and DOT 4 fluids and has higher performance.

But the CivicEater has a good point - you would waste money mixing the two together. You would get something that was a little better than the conventional fluid and worse than the synthetic in characteristics. They were made to mix for convience - you should really stick with one or the other.

Good Luck.

In my experience I have only had one it ended up in my ripping apart the engine and cleaning the junk and sludge that was in there. I run synthetic and the one time I went to a shop they put in conventional without my permission. Bad thing to do