Originally Posted by
Cossiemainful
In heat-proof for example.
What are you on about?
His particular brand of 5w30 or 10w40 could be an estersynythetic capable of taking 160 degrees of heat for all you know.
The grade of the oil isnt its heat rating, its the viscosity (thickness) thats all.
You can get 10w40 oil that takes massive heat, and others that cant cope with heat at all well, but they still have the same thickness.
And a 5W-30 mixed with 10W-40 is crap for me, even for refill.
But if ppl want to maltreat their engines with crap oil, go ahead!
People actually deliberately blend oils to get to a viscosity they want for certain uses, include the oil companies in the first place, so I dont see how the fact its got two grades of oil in now somehow makes it "crap oil" what do you mean? Crap in what way?