mix conventional and synthetic GEAR oil

mcowing

Member
Jun 6, 2010
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1988 GT, stock 8.8 rear end, previous owner changed rear gears more than 10 years ago, around 20,000-25,000 miles ago

I took the plug out for fun and it wasn't dry but I couldn't 'feel' the level with my finger. (suspension was loaded) It's supposed to be right up to the fill plug right?

I have no idea what was used. IF it is conventional, can I top it up with synthetic because it has friction modifier built in? I'm trying to get away with not changing the whole thing this season. I haven't had any problems, I guess I'm just looking for trouble.
 
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nickyb

WAIT,you now have a pair?
5 Year Member
Apr 3, 2009
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If your looking for trouble you've come to the right place.If You can feel oil with your finger then I say leave till your ready to change it.
first line is song refrence( E.P)
 
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96pushrod

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May 15, 2018
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I always just run conventional in 8.8s, some carrier manufacturers recommend against synthetics.

If it’s the stock cover then it’s supposed to be around 1/8in from the fill hole, or to the top won’t hurt.

But, you can top off with conventional or synthetic, it won’t hurt anything. They’ll mix fine. If it’s more than like 1/3 qt low I’d add a touch of friction modifier to be safe.
 
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