Topic: Why does oil have to be so confusing?

[dntsdad]

I have been reading and searching for the last couple hours and everything I find is essentially conflicting.

have a R150 tranny and a coming dual case setup.

I have read numerous times that using GL5 with kill the synchros in the trans and that only GL4 should be used, but then I read a 100 posts that say TO use GL5 in the transmission. UUUGGGGG!!

My plan was to buy 2 gallons if Redline MT90 GL4 oil and use it for both the transmission and both cases. Fill the trans, dump a qt. in the front case, and 2 in the rear case.

Can anyone clear this up for me?

[blackdiamond]

GL4 is an older spec than GL5 and when our mini toys were manufactured it's possible that GL5 didn't even exist.  Most gear oils are rated for both GL4 and GL5 specs.  I think the manual transmission MAY shift a little better with GL4 because it was designed to work with the GL4 spec, but either one should be sufficient.  Other than Redline, I'd suspect it's difficult to find a GL4 oil that isn't also spec'd for GL5.

[blackdiamond]

Well, Valvoline Conventional is listed for GL5 only and I know it's worked fine in more rigs that just mine.

Mobil 1 says, "Mobil 1 Synthetic Gear Lubricant LS 75W-90 can also be used in rear axles where API Service GL-4 lubricant is recommended." but listed as a GL-5 oil.

[blackdiamond]

Royal Purple is recommended for either GL-4 or GL-5 applications.

The bottom line is there is nothing to worry about either way.

[possume22]

from what i  read gl5 will work where gl4 is required

[jimbo74]

however, using gl5 in a vehicle that specifies gl4 may cause premature wear because there is too much sulfur in the gl5

[blackdiamond]

however, using gl5 in a vehicle that specifies gl4 may cause premature wear because there is too much sulfur in the gl5

Though I doubt that it would make enough difference to worry about.  Probably similar to the synthetic motor oil deal where it's possible to prove it's better, but conventional oil has been used in cars that lasted 300,000 miles so the true benefit is nearing zero.

[emsvitil]

I believe the GL4,5 specs are mainly performance specs.

In the case of GL4, there may also be maximum allowable quantities of substances too (sulphur).


So if the oil meets the GL5 performance spec, without going over the limit on sulphur on the GL4 spec, it's dual rated GL4,5.