gl-4 vs. gl-5 gear lube applications

[montero91]

my '91 mitsubishi montero reccomends gl-4 75w-90 in the transfer case and gl-5 or higher in front and rear differentials.could anyone

direct me to a old discussion on the difference between the two. i did a search and came up with nothing.

 

[1sttruck]

I had 183 hits on 'gl4'. Standard Transmission has gallons of synthetic GL4 Castrol Syntorq (?) for less than $60, or you can the same (?) at a Dodge dealer for a bit more if you ask for the transmission fluid for the 5 speed manual in the 2500 trucks, which is what I have.

 

[HardbodyLoyalist]

GL-5 oils contain high concentrations of sulfur-based EP/AW additives. These additives don't get along with yellow metals.

If your transmission or transfer case specs GL-4 only, then it probably contains copper or brass components that would be damaged by a GL-5 fluid.

Molakule's company carries a nice array of GL-4 gear lubes. Redline and Royal Purple also make GL-4s. You can pretty well forget about finding a GL-4 dino.

 

[Gurkha]

Actually some GL-5 oils like Mobil-I synthetic are rated safe for copper and brass, so is Elf Transaxle GL-5 as well as Delo transmission oil which is the safest as it uses boron for EP.

 

[Ken2]

quote:

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GL-5 oils contain high concentrations of sulfur-based EP/AW additives. These additives don't get along with yellow metals.

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Old tech. Many GL-5 gear oils no longer use these materials, so are safe, as Gurka said.


Ken

 

[montero91]

thanks for your reply's! i went to napa and they had a sta-lube gl4 but also had a sta-lube that met gl4 and gl5 but was hesitant to buy. so i went with the gl4.it was more expensive but i will call s-l tomarrow to see if the other wil work.

 

[HardbodyLoyalist]

Actually, I believe if you dig through past threads you'll find conflicting info on the Mobil1 GL-5. Apparently, some members have received different answers, depending on which rep they spoke to.

If anybody here has actually put 50,000+ miles on a GL-4 spec'd transmission using Mobil GL-5, please chime in.

 

[TomH]

I've had M1 75W90 in the transmission and rear end of my 94 Nissan truck for the last 70K miles. Still shifts as good as when I put it in a little over 4 years ago, and there are no strange noises coming from the rear.

Being that the M1 is dual (GL4/GL5) rated, I wasn't the least bit worried about using it in a Nissan, and so far I can see/hear no detremental effects from its use. I'm convinced.

 

[Jimbo]

The basic answer to the original question is that the differentials have hypoid gears which have extreme tooth pressures requiring GL-5 levels of EP additives and the transfer case has helical gears which do not. I just wanted to get the explanation in this thread.

Many years ago this was a real problem for those of us that had real (aircooled, rear engine) Volkswagens. The transaxles had brass or bronze syncros, and the final drive was hypoid, sharing the same oil. Hypoid gear oil made the synchros useless in 40-60,000 miles. I notice that Redline MT-90 appears to be made for these types of applications.

 

[nissantruckguy]

I have owned 4 Nissan trucks. All 2wd with 5 speed trans. 90 reg cab, 200,000 miles one clutch and trans was starting to loosen up when I sold it. 94 extra cab, first trans went at 125,000 was about to eat a second trans when "retired" (t-boned while parked at night),300K.next, 97 reg cab 1st trans expired at 125, second at 200,000, third is needed at 383,000 and it is now semi-retired. The new truck is a 2001 king cab with 75,000 miles. It just got Redline MT-90 in the trans. No one, not a single mechanic or even the Nissan corporate people told me to only use GL 4. I was using Valvoline or Castrol GL-5 75-90. Now I know better and will keep this forum posted on the new trans. I drive 60,000 miles a year with lots of weight in these trucks, at least 1000 lbs in the bed. No towing just weight in the bed. I deliver frozen fish all over western Colorado so each week I traverse the continental divide. Two mountain passes of 11,000 miles do not make for easy driving. My trans gear lube change intervals were 30,000 to sometimes 40,000. I think with the redline that should be reasonable. With the Dino gear oils it was not.

 

[gtx510]

quote:

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Originally posted by TomH:
I've had M1 75W90 in the transmission and rear end of my 94 Nissan truck for the last 70K miles. Still shifts as good as when I put it in a little over 4 years ago, and there are no strange noises coming from the rear.

Being that the M1 is dual (GL4/GL5) rated, I wasn't the least bit worried about using it in a Nissan, and so far I can see/hear no detremental effects from its use. I'm convinced.

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Mobil1 ISN'T dual GL4/5 rated. It's GL5/MT1 for synchroless transmissions and rear diffs.


Redline MT90 or 75W90NS are both GL-4.

 

[Audity]

Question for the group - has anyone here run across a legit case of brass or bronze transmission components being damaged by a modern, quality GL-5 oil? (except perhaps in the case of an old classic)

I recently did the changes in my S4, dutifully using Redline MT-1 in the transaxle and RL 75-90 in the rear diff. The guys on the Audi boards all scream YOUR CAR WILL BLOW UP!!!! if you do it differently.

Call me sceptical, but I think it would probably have been fine if I had just used M1. Gotta say, though, it's shifting slicker than goosefudge.

 

[Winston]

This has been discussed many times here. I think the issue is that the GL-4 fluids have additives that help the syncros work better. The GL-5 fluids do not. Most newer GL-5 fluids will not hurt brass parts. However, they will not provide shifting performance as good as a GL-4 fluid would.

If you want a good Manual transmission fluid, go with Redline or Mola's Specialty forulations products.

Type in GL4 in the search engine, you will find many discussions on this subject. Pay special attention to Mola's comments.

 

[Auto-Union]

Good answer. I've heard of M1 in newer trans w/o problems. The only way I'd use GL-5 in a transmission is if it had a whining problem and go thicker w/GL-5 140.

 

[Big Jim]

Actually the biggest issue isn't GL4 or GL5, it is if the product is blended with manual transmission use in mind. GL5 intended for diff use may not work very well in a manual trans. GL5 blended for manual trans use will be fine in a manual trans.