Synthetic Oil in 76
 

Ok guys I have a 76 K15 with a 350 motor with maybe 3500 miles on a rebuild. I want to go full synthetic. I have Mobil 1 5W40 in it now. Im thinking of going Royal purple in everything, motor, 4spd, transfer case, front and rear ends.

Which one you recomend and what weight would be great, I know I need 90 weight or so gear oil but what about the motor

I went Mobil 1 everything........all except the battery acid!
RP is probably just as good.......who knows?.....

Amsoil is some really good stuff. First oil company to make synthetic I think. They're a little expensive but its really good stuff. My brother is a dealer, and before that my uncles was, so I guess you'd say my family are 'amsoil purists.

RP is high- I think because of all the expensive Race cars they sponsor?? not that i don'r like race cars but - I buy amsoil when it's on ebay for BIN prices but i had to use Mobile 1 this time. $5.25 a qt. 10K out of an oil change though. My tranny & rear have it also in the Dodge. My tranny popped a line this winter and I ran it(unknowning) until the tranny wa s slipping like crazy and then finally wouldn't move. I fixed the line, refilled and the $2300 BD tranny is fine . something good to be said for synthetics. DAVE

I wouldn't go 10,000miles between oil changes but synthetics are good stuff. I use semi-syn's in my trucks since they get the oil change ever 3000miles regardless. These old type engines leak past the rings more then new ones and dirty up the oil real quick, so keeping that oil in after 3k isen't a great idea IMO. That said my girlfriends 03 civic gets mobil 5w20 sythetic and a change every 6000miles, by 3000miles the oil is only just starting to change color and smell [I do change filters every 3k though]

I also run mobil syn 75-90 gear oil in the differentials.

I do change the filter at 5K