Never heard of 11w40. Would have slightly thinner cold properties that 15w40. Second Opinion: I've never heard of 11w40 either. As far as I know there is no such thing.
15 is thicker oil and for bigger engines.
15 is thicker oil and for bigger engines.
Only the weight of the oil, 20w 40 is thiker than the 15w40, 20w 40 is the best oil for the old cars although 15w40 is very easier cold start ...
The main difference between 10W-40 oil and 15W-40 oil is that 15W-40 oil has a higher viscosity than 10W-40 oil. 10W-40 oil allows the engine to run freely.
15W40
15w40 is thicker at all temps vs 10w30.
Oh, dude, it's like this - the numbers represent the viscosity of the oil at different temperatures. The "15w40" means the oil flows like a 15-weight oil in cold temperatures and a 40-weight oil in hot temperatures. The "15w50" flows like a 15-weight oil in the cold but a 50-weight oil in the heat. So, the main difference is how thick the oil gets when things start heating up.
Yes, you can mix conventional oil with synthetic oil with no problem.
It takes 15 quarts of 15W40 diesel oil I highly recommend Rotella 15W40
15w40
15w40(CH4)
15W40