I am thinking of switching to a synthetic oil for my 68 pontiac firebird 400. Up until this point i had never really considered synthetic as the big 6.6 liter at 400hp is not all that hard of a working engine (redline is right at or slightly above 5k). it does however run a little bit dirty compared to never designs and pontiac v8s are known for running a little hot. the car is driven approximately 2000 miles per year and sits for 8 months with only periodic start-ups. I am wondering if it is time to upgrade. the car has hydrolic lifters and basic stamped steel rockers. I am wondering if there is any danger is changing to synthetic after all these years of conventional. can conventional and synthetic be mixed? any thoughts? is mobile 1 as good as say...royal purple? I run 10w30 all year in her.

There has been some discussion lately in the older
classic boards 444-544 about synthetic not keeping
the old gaskets swollen,and subsequent oil leaks.
Yes some do run 50-50 for just that reason.
Bob's the oil guy has a site that is very informative.
With those pesky sometimes sticky hydraulic lifters
it is wise to keep the oil clean.
Ken
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69-145-S ; 71-145-S ; 72-145-E ; 72-1800-ES ; 87-245-DL