Mt Bob
Minister of Fire
I run syn in my vehicles,and run it 2 times as long a reg(standard procedure) so cost wise is the same.Have been doing this for years.Being a mechanic have seen oil go through many changes,the early syns DID leak past seals,parrifin plugged up lots of motors,etc.Experienced syn problems (2 stroke) in snowmobiles and waverunners and outboards.By the way,quick lubes still buy cheap oil and advertise/sell it as another better product!Your better smaller oil companys(like bg) have some very high quality diesel oil for big rigs,50,000 mile plus,just change filter and top off at perscribed intervals.Very expensive,non syn,but saves the truck companys a lot of money.