I really appreciate hearing from everyone about how yours acts, and feel better knowing that it's not something I should be concerned about. I have shell rotella 15w 40 in the truck. Thats what the previous owner ran in it since new, so I continued the same oil. I was under the impression that I may be asking for trouble if I switched to synthetic after using dino all this time???? Is that not the case. Can I run synthetic in the winter and regular oil in the summer, or should I switch to synthetic all the time. What are the pros and cons to switching??? Thanks again.

 

JMOP 50 years ago when I started pulling wrenches the oil was crap. sludge would build up 1 in deep around the valve springs and other places because the aditives were not much count. Then when you changed a brand of oil that used diff additives there would be gobs of sludge brake loose and plut oil passages. The word was do not change brands of oil. And now the oil is so good you see very little sludge and I think you can switch back and forth at will. I use 15-40 dello my self and our temp gets down to 20* at times to 100* in the summer. If it got colder I would use a 5-40 synthetic. I think it does a better both hot and cold. Just costs more.
I do use synthetic in my trans.

 

You ain'y lying Larry. Back in the day oil wasn't as good as it is in today's standards. Back when my dad changed oil in his vehicles, Quaker State oil was terrible with sludge. A close friend of his ran only that oil and they both tore the top end of his motor down and it was loaded with sludge. Welcome to FTE by the way...