Tranny and Rear End Gear Lube

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canbeam
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Tranny and Rear End Gear Lube

Postby canbeam » Sat Jun 10, 2017 10:59 pm

Spent most of the last two days researching the internet and talking to a half a dozen parts guys and mechanics about the right kind of gear lube to use in my Tiger tranny and rear end with LSD. One guy is a mechanic who spends most of his time working on classic cars at a well known speed shop. I got about 6 different opinions.....lol I trusted the classic guy the most, and he uses Pennzoil 80W90 API GL-5. This is a non-synthetic dino oil, as he warned never use synthetic oil in the older cars. I bought some from his supplier and came home with it late yesterday. Then I poked around on the internet some more and came across this article on GL-4vs GL-5 oil. The article is at http://www.widman.biz/uploads/Transaxle_oil.pdf This is an excerpt:

A traditional GL-4 gear oil of any given viscosity has about ½ of the level of sulfur/phosphorous additive that would be in the GL-5 product, so the bond is not as strong, and therefore can be peeled off without peeling a layer of brass (or less brass). This means that the GL-4 product provides a little less extreme pressure protection, so in the differential of a high-powered car, it would not be the ideal product in the differential. To understand this need we should be aware of the fact that the differential is where the final torque is applied to the wheels (in most applications).But in the transmission, we should consider two factors:

1. Do to the fact that the differential applies the final torque, normally we do not need the full EPprotection in the transmission where less torque (about 30%) is applied.

2. We need to be able to break the EP protection to stop the spinning of the gears long enough to mesh them or synchronize them.
When we use a GL-5 product in a transmission that requires GL-4, we normally find 2 to 4 times as much copper in the used oil as we would with a GL-4 product (with used oil analysis). Eventually the synchronizers wear to the point that they no longer make contact with the other half of the cone, bottoming out before stopping the opposing gear.


Even though I have tremendous respect for the classic car guy, I got nervous about Pennzoil in my tranny after reading the above, as even though the Pennzoil is non=synthetic, to be a GL-5, it must have sulphur, which eats at the synchros. I ended up ordering Brad Penn GL-4 classic dino oil from Amazon. I'm going to use this in the tranny.

Now debating whether to use the GL-5 Pennzoil or the GL-4 Brad Penn for the rear end. I was told to use the friction modifier with both of them. I'm leaning toward the Pennzoil, as I drive fairly aggressively, my Tiger has about 370 hp, and I don't think there is any yellow metal to worry about. (shims maybe?) I've never taken a rear end apart so not sure if there is an issue.

Talked to a local Tiger owner at a car show this afternoon who bought his Tiger new, and has a hipo supercharged Tiger with a ton of hp for many years, and he says he runs nothing but synthetic lube in both his tranny and rear end, and has never had a problem. Maybe I'm fretting about nothing for the low miles I put on the car every year.

Any thoughts?

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canbeam
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Re: Tranny and Rear End Gear Lube

Postby canbeam » Mon Jun 12, 2017 7:43 pm

Receiving Brad Penn GL-4 oil tomorrow from Amazon, and going to use it in the tranny and rear end, with the friction modifier for the rear end for the LSD.

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sunbeam2005
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Re: Tranny and Rear End Gear Lube

Postby sunbeam2005 » Wed Jul 12, 2017 6:36 am

I use a straight 70w/90 gear oil with Kindle LSD additive has worked great for many years, a note its also good for AT's as a friction modifier. 8)
George Coleman


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