Mixing regular oil with synthetic. Safe???

[Shurup]

One autoshop here (with bad reputation among the auto advanced people) is saying that mixing regular oil with synthetic will not harm your engine. On the other hand, my body who is a very good mechanic (being a mech for a very long time - a lot of experience) saying that mixing regular with synthetic when temperature is high will produce jell-like substance wich will clogg oil filter, oil pump and eventually kill the engine. That's why he highly recommends flushing the engine thoroughly and go to semi-synthetic first before swithing to pure synthetic.

Do you have any commens on this?

 

[TheRookie]

trust your budy and not the crappy shop. the 2 dont mix well

 

[Robb]

I have heard of many people recommending using 1 quart of syn. with a dino oil change. I am not saying it is good or not because I have never tried, but I have heard it from many trusted people. They say that adding a quart of syn. to a normal oil change will add a lot of the benefits of syn without the cost of a total syn oil change.

Like I said, I have heard this from trusted people, I am not sure if it is true.

Robb

 

[mrboyle]

I would not recomend mixing different oils. Each oil has its own chemical make up and mixing them can cause the chemicals to react aginst each other.

 

[RiverRat]

So what about Valvoline DuraBlend? That's a synthetic blend. Isn't that part dyno and synthetic oil?

 

[Doug]

I would not recommend mixing oil... it can gum up inside the motor and thats bad. as far as blended motor oils im not 100% sure how they work but theyre made so they wont mess up your motor.

 

[Shurup]

OK mixing different oils IS bad. What about going from regular to synthetic without a good flush? There still will be some oil left if you just change the filter and the oil and don't flush your engine.

Is the amount or that oil left in the engine enough to produce that jell like substance (gum???) and to harm the engine?

And what about tranny, t-case where the temperature don't rise that high as in the engine. Is that bad if I just change regular fluid to synthetic without a good flush?

 

[Magicfan25]

Look at any synthetic oil site, mixing the two will NOT hurt the engine. I dont know if mixing one quart syn actually helps anything or not. But mixing the two together is wasting money. When you mix the two, you can no longer use the extended drain interval offered by synthetic.

As mentioned before, there are synthetic blend and those are safe too. Little better protection, but no longer drain interval.

Mobil 1 with SuperSyn™ is fully compatible with conventional motor oils, semi-synthetic motor oils and other synthetic motor oils should it be necessary to mix them. But the superior performance of Mobil 1 with SuperSyn™ will be reduced by diluting it.
~~from Mobil1.com

 

[aldive]

Mixing synthetic with dino oil will not cause any troubles. But why not just use synthetic to get all of the benefits?

 

[wpurple]

Mixing the 2 will do no harm, Synthetic IS dino oil, just refined slightly differently.
It even states it on the bottle that it is compatable with all conventional oils.