it is just what I have heard about the way oil breaks down, and I said that synthetic does not break down as fast, but what I said about using different types of oil in different weather climates is that if it is hot outside like in the southern states then most people will go with a cheaper oil, not meaning a cheaper grade but we all know that synthetic is alot more expensive and I know me personally I like to change my oil more times when it is the dead of summer because not only do you have engine heat but also when the temp outside is hot, like day before yesterday it was 106 at 12:30 in the afternoon then the oil is staying hotter then in the colder months, and just makes it break down faster.

So my question is that if I have lets say 3.5 qts. of synthetic in the pan can I put in regular 10/40 for the extra quart that I need?