I use conventional 75w140 in whatever brand was easiest for me to grab off the shelf. The Dana 60 in my 3800+ lb cuda had the same oil in it for 12 years and saw 2 years worth of 10 sec passes, then 10 years of 9 sec passes w/ a few 8 sec runs right before I pulled the cover off for inspection. Not to mention a whole lot of street abuse.
Everything looked great inside. Just swapped the 4.10 out for a 3.54 over Thanksgiving and the gears looks great.
No more than 2 quarts.
Not saying synthetic isn't good, or any other type of oil is bad...just saying the regular cheap stuff works just fine.
CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax
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