Mixing different weights of oil

RalphVa · Jan 16, 2008

Why not use 5w40 all year round? Even 5wxx is heavier at startup than at operating temperature. 0w40 would be even better year round and would STILL be heavier at startup than at operating temperature.

Ralph

DieselPower · Jan 17, 2008

Mixing different oils isn't suggested even if it's the same manufacturers oil. Different viscosity oils even from the same manufacturer and "brand" can have different additive packages. When you start mixing already blended oils your throwing out millions of dollars of research that go into blending and testing specefic oil blends. Mixing base stocks and mixing final finished blends is completly different. If your mixing base stocks here's a handy calculation tool Viscosity Index Calculation page

WantedWolf · Mar 6, 2009

I searched the posts, and found little bits of help, I wont mix weights for engine applications, but I should be able to mix 10w30 x 15w40 just this once for the hydraulic system, (not HS). I got some Bio stuff to replace all but I dont want to drain till I get to the shop and the hours wont be due for a month.

ihookem · Mar 13, 2009

I have mixed so many different oils it ain't funny. One time I mixed straight 20w with 5w30 and a qt of 10w40. Don't matter but it was an old 70 Nova.

phyxer · Mar 17, 2009

Well my truck holds 40 guarts (cummins M11 in a Volvo 610). As far as mixing, I'd say that as long as you mix to high quality oils then you should end up with a high quality oil....makes sense doesn't it? I normaly don't mix oils because I usually try to make sure I have spare oil around for all of my equipment. I have however been in situations in the past where I have mixed brands and weights and I have personally not noticed any ill affects to my equipment. I would personally not be afraid to do it again if need be. That's just me though, others will disagree I'm sure

Troy

sandman2234 · Mar 17, 2009

I just changed the oil in my p/u and found that one quart of the yellow quarts was not the same as the rest. I figure it will just thin the rest out a little, but since I use a heavier oil than recommended, it probably won't hurt.
David from jax