API GL5 and GL4

**t_marat** · 10-21-2006, 09:02 AM

I bought a Valvoline 75W-90 oil for the differential and has put it in. Later I noticed that it is API GL4, and that there are other transmission oils which API GL5. Is it fine to leave the oil as it is or should I change to GL5?

**Kobe Diesel** · 10-21-2006, 10:21 AM

GL5 is for differentials
GL4 rating is for manual transmissions. GL5 has some additve that is not good for transmissions.
To be safe, change it.
Are you using synthetic gear oil?

**t_marat** · 10-21-2006, 10:34 AM

The one I put into the rear differential is a semisynthetic
http://www.valvolineeurope.com/index...3ca705c1f93e12
The GL-4 one. Didn't know about various GLs until I saw another gear oil with GL-5 marking.

Gearbox has Mobil1 ATF.

**t_marat** · 10-21-2006, 10:35 AM

Really do not want to change it. Just put it in. So much waste..

**KenB** · 10-21-2006, 11:10 AM

I didn't know I had an LSD until I got the spec sheet from the board here.
(Thanks again to Ausmpower)

I had the rear oil changed 2 years ago and don't know if my indy put in the right stuff, I guess I'll change it soon to make sure; along with new blue coolant, brake fluid change and tranny.

**t_marat** · 10-21-2006, 02:15 PM

Anybody can say anything else? Dump the new (GL4) oil and go for GL5?

**Bellicose Right Winger** · 10-21-2006, 04:07 PM

You really need to change it. GL5 lubes have additives, used to be sulphur that make them suitable for the Extreme contact Pressures that occur with hypoid gears. Sometimes you'll see EP on the label. These additives prevent the metal to metal transfer between pinion and ring gear. Sulphur was/is a problem for brass synchronizer rings which is why transmissions use GL4 lubes.

Paul Shovestul

Originally Posted by t_marat

Anybody can say anything else? Dump the new (GL4) oil and go for GL5?

**BillionPa** · 10-21-2006, 10:05 PM

i would continue to use either ATF or an MTL specifically designed for manuals that spec ATF.

Personally i would use Redline D4 ATF as it stays fluid in very low temps (im using it currently) and provides GL-4 protection to manuals, and has high temperature stability from the new Dextron 4 spec.

also, since your transmission is a manual (and im elaborating my response from your other thread) add a tube (50 grams) of lubro moly molybdenum disulfide gear oil additive to every 2 quarts of fluid required in the tranny. that will make the fluid act similar to GL-5 but will be far superior for your car. it will shut the whining in your tranny up REALLY GOOD!

and yes i know you cant get Redline where you are at, so have it imported or something!

**t_marat** · 10-22-2006, 12:31 AM

OK, thanks everybody.

**t_marat** · 10-22-2006, 09:12 AM

Changed the fluid to Chevron GL5.
Interesting is that the Chevron is cheaper that Valvoline (GL4) and Essor (GL5), all 75W-90. I always regarded Esso as the Mobil for the "poor", as they are both ExxonMobil trademarks. And here is a Chevron, which is even cheaper. There was also Mobil1 SHC-LS GL5 full synthetic, costing 2.6 times more than Chevron. Mobil1 GL4 oil was even more expensive, 2.8 times. Must be because it was in a cool black canister

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