Redline Lightweight shockproof or MTL for a Getrag 245 5 speed.

[FranzE21]

What do you fellas think. I personally see no real benefit of the MTL vs the shockproof for a hotted up car. Just wondering if someone knows something I don't.

Also, might put heavyweight shockproof in my new smallcase LSD. Any objections?

Hal

[DHoang]

I would use either the light (or heavy shockproof, depending on) if the car sees any track time.
THe advantage of the higher viscosity of the shockproof formula (outside of the improved cushioning the gears) is that thicker viscosity also reduces air bubbles (cavitation).

For hi perf street use, I'd go no higher than the lightweight shockproof.
The heavyweight shockproof could prove to be too thick on our 4cyl trans & either sap too much power due to increased fluid friction and/or cause the shifting to be too notchy.

[FranzE21]

Thanks for that mate. Anyone else got any opinions?

[E21Adam]

Only time I ever used shockproof was in an old Ford Bronco. It actually lubricated the POS transmission so well that the synchros were over-lubricated. Ended up busting a synchro, and had to have the tranny rebuilt by a friend who was a Ford tech. I guess my point is it's really good stuff; just make sure it's inline with what the synchros need to operate without grinding.

Tangent: Did you know Fiat 124 Spiders can only use GL-1 tranny oil? The easiest place to get some is to go to Tractor Supply and buy gear oil for a 1939 Ford tractor. Normal transmission oil will have you destroying synchros in no time because they spin too fast. This is, of course, assuming the car doesn't rust through first.

[FranzE21]

I was talking to a redline guy in Perth. He handles all the regional motorsport something etc. very nice bloke, obviously knows his shit despite the lack of detail from what I remember about him.

Gearbox he recommended Super Lightweight shockproof for ideal performance on and off the track, which has the same fluidity as the MTL, but with shock protection. He said if you wanted to put a little bit of a hole in your pocket, try the lightweight shockproof first, but he warned that sometimes getrags baulk and don't like it when cold, no damage is sustained but its very viscous when cold.

He recommended the 80w 140 diff fluid for the LSD. Plenty of heat protection without much chatter etc. sounds good to me.