Re: Rear Gear Lube - Synthetic Or Conventional?
 

I use Amsoil Severe Gear Sae 75W-110 Synthetic Extreme Pressure Lubricant. It's a premium grade extreme pressure (EP) lubricant engineered specifically with "High Film Strength" for high load demands.


It's also compatible with conventional and synthetic gear lubes and most limited slip differentials.


Plus it's recommended for applications requiring 75W-110, 75W-90, or 80W-90 gear lube with any of the following specifications: API GL-5, MT-1, MIL PRF-2105E, Dana SHAES 234 (Eaton PS-037), Mack GO-J, or the differential gear lube specifications from GM, DaimlerChrysler or Ford.

Re: Rear Gear Lube - Synthetic Or Conventional?
 

Redline heavy duty shockproof in my Dana no problems.

Re: Rear Gear Lube - Synthetic Or Conventional?
 

Same here, (and light shockproof in the Jerico)

Re: Rear Gear Lube - Synthetic Or Conventional?
 

We run all Strange products with Royal Purple. Never had an issue. (Knock on wood)

Re: Rear Gear Lube - Synthetic Or Conventional?
 

We have run Qualifying Driven oil in the Challenger Rear with no issues and a 4.88 until I went to 3470+ lbs. At 3250 no issues for 2 season. At 3470 we hurt gears. They are not Pro Gears and its only an 8 3/4.....so keep that in mind.

Switch to the Driven's Speedway Synthetic oil in Challenger and have always ran in COPO with no issues. Its VERY light.....

I do break in for 3-4 passes with No Synthetic Driven Break in or Torco oil from Mark Williams.

As far as an A to B to A test - never done - doesn't matter since I won't run a light weight non synthetic in the rear or trans anyway - we have enough other **** to test when we go out!

Re: Rear Gear Lube - Synthetic Or Conventional?
 

Amsoil Severe Duty for me

Re: Rear Gear Lube - Synthetic Or Conventional?
 

My opinion, your results may vary.
Conventional gear oil, cheap and readily available and designed for rears. So cheap that changing it every year is a no brainer. I install rare earth magnets in engine,trans and rear to catch any wear particles which is what wears out gears and bearings. Drain,clean and refill and your rear will last.
Synthetics are usually thinner and will flow well, also made to withstand heat which drag cars usually don't see. Cost more but you're only using 2 quarts so it's not a bank breaker. Possibly a little better lubrication and possibly worth the peace of mind but not necessary on a drag car.
Shockproof doesn't make any sense to me. thick as mud and it's claim to fame is it clings, so does axle grease! Might be great in a roundy round car where the rear gets very hot. I want thin oil that flows all of the time.

Re: Rear Gear Lube - Synthetic Or Conventional?
 

I don't know that it's an oil issue. I bracket raced my Dart with the 8 3/4 for ten years at around 3250 lbs. When I started running it in SS/JA a 3470+ lbs. I took teeth off the gears three times. I switched to a Dana, haven't touched it since and I'm running the qualifying oil. IMO it's more of a gear strength issue and I don't think it would be an issue if pro gears were available for the 8 3/4 in the ratios we need them. Just my 2 cents :)

6383 SS

Re: Rear Gear Lube - Synthetic Or Conventional?
 

This is my first go around with Redline in the diff.. Using super light shock proof, I'm @ 3650 w/me but I'm slow. 5.14's in a 9".

Re: Rear Gear Lube - Synthetic Or Conventional?
 

I have to assume that you have not used the light or heavy Shockproof gear oils offered by Redline. It is not at all thick, I`d guess it flows like a 30W engine oil, and it definatly does cling. A couple of years ago, I pulled the cover of my Mustangs 8.8" rearend after sitting all winter, and the top of the casting was still wet with oil. Both my cars are 4 speeds, and I use the Redline light shock in the Jericos, and the heavy shock oil in the diffs. My 10.0-9.9 ET bracket car has a Dana 60, and and has been a stick car for 15 years now, the gears always look like new. I think some gear ratios are more likely to break than others, especially when you get into lower ratios. I`ve been racing my Mustang for 13 years now, the same set of 4.88s still look fine, but I have broke 2 sets of 5.14s, which have 1 less tooth on the pinion than the 4,88s do, From what I have seen with 8 3/4 MoPars is that with the steeper ratios, the teeth on the ring gear get quite shallow, which can`t be good for strength.