The Mixing Of Oils.

[Rich]

Hey!

I am currently running Valvoline 5w30 in my car. The engine has some internal modifications but is getting very close to a rebuild. I have a very small amount of oil loss due to some minor valve train problems. Rebuild will be coming in April / May. Anyways, I need to top-up the oil every once in a while. The other day, I noticed it was a bit low and asked my mom to grab me a quart from the mall since she was going out. She bought synthetic by mistake and I came within inches of pouring it into the engine, before I noticed that it was synthetic.

My question is, would there be any damage to the engine if I had ran a mix of synthetic and the normal 5w30 in there?

Would it make a difference if the engine has modified internals like mine (cam,crank)?

Im hoping that the problem never arises, but it would be nice to know.

Thanks
--Rich

[texan]

Nope, it shouldn't cause any problems. Granted you'll have a little bit of the superior stuff mixed in with the garbage , but that's just something you'll have to live with. It is highly recommended that your oil be homogenous if possible, so in the future I recommend using the synthetic only for engine oiling duties. Especially after the rebuild, which I assume is a performance minded one .

[Polygon]

I would agree, Texan hit the nail right on the head. But he doesn't need me to tell him that.

[GTStang]

I agree just noting that after thr rebuild you should use non-synthetic oil during the break in process. This is very important ask any quality engine builder