Real deal on GL-4 and GL-5 gear oil

[bronz]

Can somebody fill me in on the differences between gl4 and gl5 rated gear oil. I accidently put in gl5 75w90 mobil1 gear oil in my transmission. should i be worried and change it out right now or i will be fine runninging it? thanks

[Jman25]

is your car manual? I put redline gl5 75/90 into my diffs front and back and the front shares the transmission so if youre running a manual then youre fine, dont know about if its an automatic since I dont have one.

[bronz]

yes im manual. ive heard that gl5 is thinner than gl4 and might wear out transmission faster

[99blueb5]

uhm im pretty sure thats just the rating, gl4 and gl5 75-90 should both have the same viscosity hence they share the same 75-90 weight rating

like royal purple has a gl4 and gl5 rating: http://www.ecstuning.com/Audi-B5_A4-...sion/ES263484/

from mobil 1 site: http://www.mobil.com/USA-English/Lub..._LS_75W-90.asp

"Applications

* Mobil 1 Synthetic Gear Lubricant LS 75W-90 is recommended for use in modern high performance automobiles like SUV's, Vans and Light duty trucks requiring API GL-5 and MT-1 level performance
* Mobil 1 Synthetic gear Lubricant LS 75W-90 is intended for initial fill, topping-off or refilling differentials, final drives, transfer cases and other gear applications where lubricants meeting API Service GL-5 and multi-purpose or mild EP gear lubricants are recommended
* Mobil 1 Synthetic Gear Lubricant LS 75W-90 can also be used in rear axles where API Service GL-4 lubricant is recommended
* Not recommended for automatic, manual or semiautomatic transmissions for which engine oil or automatic transmission fluids are recommended
* Where extended service intervals and warranties are required"

direct from there site, look at bullet point number 3

[Seerlah]

Property values are different and you should change to GL4 asap. The compound element eats at a part of the transmission (can not recall what part) if you place GL5 in there.

Place GL4 in the tranny and GL5 in the rear diff.

[old guy]

Gl-5 oils contain more sulfur which eventually eats away at the brass syncros. Gl-4 is better formulated for the transmission. You don't have to go out immediately and change it out, but long term it would be a good idea to replace it with a Gl-4 gear oil. Gl-5 is fine for the differentials.

[tttomdemaria]

Gl-5 oils contain more sulfur which eventually eats away at the brass syncros. Gl-4 is better formulated for the transmission. You don't have to go out immediately and change it out, but long term it would be a good idea to replace it with a Gl-4 gear oil. Gl-5 is fine for the differentials.

i changed my gear oil in my trans when i did the clutch. i put pennzoil gl5 75w-90 in. about a year later i have no second gear syncro and my center diff knocks like fuck when i turn. change it the fuck out now.

[tttomdemaria]

i changed my gear oil in my trans when i did the clutch. i put pennzoil gl5 75w-90 in. about a year later i have no second gear syncro and my center diff knocks like fuck when i turn. change it the fuck out now.

also, sorry to bring this shit back from the dead.