sage52•21d ago

Old timer told me to run 20w50 in my 7.3 and I called him crazy

This guy I work with, been turning wrenches since the 70s, told me to swap to 20w50 in my 7.3 Powerstroke after I hit 200k miles. I told him straight up that's too thick for a HEUI system, said he was living in the past. Well after 6 months of fighting stiction issues and hard starts in the winter here in Minnesota, I finally tried his way last November. Truck fires up way better cold and the injector noise dropped off a lot. Still bugs me that he was right and I wasted all that time. Anyone else run thicker oil in a high mileage 7.3?

2 comments

2 Comments

simonw4121d ago

Buddy of mine ran 15w40 in his 7.3 for 300k miles and it purred.

sagea8820d ago

And you know what, @simonw41 that 15w40 he ran probably worked fine because he wasn't in a deep freeze like we get here. The real trick with these 7.3s is that once the clearances open up past 200k, the thicker 20w50 actually helps the oil pump keep pressure up at idle. I noticed my oil pressure gauge stopped dancing around after I switched, and the top end tapping quieted down a ton. Just don't try it if you live somewhere that sees single digits regularly, the HEUI system will hate you for it.