oil questions (5W-30 vs 10W-30)

Mixing multigrades is not something I would do unless there was no alternative. Just a personal opinion.

Just a guess, wouldnt the two sets of long chain polymers just mix together provided the 2 oil-bases were similar (not mineral and detergent for example) and you'd end up with 7W-30? :-)

Jason

Yes it is OK. It would be preferable if they were the same brand, but even if not it probably would not hurt anything.

they say never mix the bottom numbers

Who is "they?"

Ed

So it's not like using 50% 10W and 50% 30W will give you 100%

In a multi-grade oil, a polymer is added to the lower weight base oil that allows the viscosity to change at higher temps. When the polymer additive wears out you'll end up with a thin base weight oil.

snipped-for-privacy@gmail.com wrote:

=== Best idea is to use only that oil type and viscosity recommended for your engine in the owner's manual. Why would you consider mixing oil viscosities rather than just buying the correct grade?

Maybe he has some laying around his house and wants to use it up.

Mixing the two oils is fine. Some people on this newsgroup are raising ridiculous concerns. Most dealers use 10W-30 even though the manufacturer recommends 5W-30.

Yep, that's exactly it. I've got way too much 5W-30, and not quite enough 10W-30.

Which is good too, right? Less engine wear. Although perhaps slightly worse fuel economy...

Michael

Well that could be a problem... creating a new viscosity than either original bottle... chemicals are funny that way.

I guess I'll just use up my 5W-30 in my '96 camry during next winter. Spring's here... too hot to use 5W-30 in the '96 in Sacramento.

Michael

You would probably get something close to 7W-30. Its not that big of a deal to mix oils.