Synthetic rear gear oil

has anyone tried Synthetic gear oil like mobile1 or the GM Synthetic in there older van?

I'm afraid the Synthetic oil will leak past the pinion seal, and axle seals. my van has 99,000 miles on it, and I do plan to start towing, so I figure it's time to maintain the rear.

do I need the posi additive with the Synthetic for my 1995 limited slip diff ?

I have an abundance of the GM Synthetic gear lube for my 03 denali, and I'm wondering if it's safe to use in my 95 AWD safari.....

has anyone tried Synthetic gear oil like mobile1 or the GM Synthetic in there older van?

I'm afraid the Synthetic oil will leak past the pinion seal, and axle seals. my van has 99,000 miles on it, and I do plan to start towing, so I figure it's time to maintain the rear.

do I need the posi additive with the Synthetic for my 1995 limited slip diff ?

I have an abundance of the GM Synthetic gear lube for my 03 denali, and I'm wondering if it's safe to use in my 95 AWD safari.....
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hello fellow van owner. I should first tell you that if yoiur rear seals are NOT NOW LEAKING, then you should not worry that a synthetic gear oil will cause it to leak. I can say this with absolute certainty, since years ago I switched to AMSOIL lube; at the time i was driving commercially & had over 100K miles on my dodge van. I installed the full synthetic line (eng.,trans.,rear end, grease for all grease fittings) & immediately niticed a reduction in rear end drag-friction that I could let off the gas much earlier as I exited the freeway system at each offramp. I now have a '90 safari; purchased at 102K miles & installed the MOBIL 1 FULL LINE as previously done. I use the FRAM EXTRA-GARD SYNTHETIC FILTERS & MOBIL 1 15-50 wt. oil. I now have 263K+ miles. the rear end (3.73 ratio w/posi-traction) growled slightly at that time. This month the noise became noticably loud, so I had a shop investigate & found that the ring&pinion & posi. were worn out so I had them replaced. that means that the synthetic oil allowed no failure for over 160K miles. I hope that this has provided yoiu with sufficient info. to go on with your van.

you got 263k miles on the orig motor and tranny ??
WOWWWWWWWWWWWWWWW !!!

you got 263k miles on the orig motor and tranny ??
WOWWWWWWWWWWWWWWW !!!
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NO!!!! I rebuilt the trans. at around 104K mi., & the engine had had various repairs (blown head gasket, etc.) at around 200K mi. I had a total enging failure back in June of '02 & then rebuilt it with lots of performance upgrades. so tell me what you think of the info. that I provided you about the syn. oil.....

I'd be impressed if you go 260K miles on the original motor and tranny ;-)
I'm at 103,000 all original drivetrain.