Originally Posted by DaveRS23
I wouldn't doubt that some oils would tend to leave more deposits than some others. But my personal experience is that the vehicle's daily operation is much more of an factor.

For instance, I began my Mopar experience by using the engines from retired police cars. Never have I pulled an ex-squad down that had those kind of deposits. And all of them had a ton of miles. But they had spent nearly all of their operational time at full operating temp.

But I have been into many low mileage engines with that kind of sludge. Most of them were primarily driven around town, running errands, stop and go from home to the store and back without the opportunity to fully warm up.

I have read that when oils are slightly heated and then allowed to cool, that the parafins in them tend to separate out and deposit. While getting the oil up to operating temp and kept that way for a sufficient amount of time, keeps the parafins suspended in the oil.

Modern oils resist that better than earlier oils, but sludging is still possible. And then engine design plays a role too. Think the 2.7 from 20 years ago. In other words, there are a lot of factors beyond simply the brand of oil that plays a role in engine deposits.

And although I haven't done it for 40 years or so, we used to flush engines with kerosene. I was actually taught it in auto mechanics class in high school.

twocents


Makes sense, seems the people that had us change their oil never had a problem, same brand oil all the time. I wonder if using various brands would maybe cause the problem. They used to sell motor flush, but kerosene just flat worked every time.