Transmission / Gear Box Oil

Glen · Post by **Glen** » Mon Dec 01, 2008 6:56 am

I have recently purchased a M38A1 170 (1953) Ambulance and would like to know the european equivalant of the gear box oil and the quantity required. If anyone can help it would be much appreciated.

GPA · Post by **GPA** » Wed Dec 03, 2008 2:34 am

Hi,
A couple of gear oil types wich should be available in most European countries are Chevron RPM SAE 90 or BP Gear oil 90 or Castrol ST90 in their Classic Oil range. (Oil salesmen will probably try to sell you some modern multigrade.) Fill it slowly to the bottom of the filling hole. If you buy about 5-6 liters you can top it up later with the same type of oil if you have a leak.
Good luck with your new Jeep.
Zoli
M38A1

GPA · Post by **GPA** » Wed Dec 03, 2008 4:49 am

In addition to the post above: SAE 90 equivalent ISO 220.
On some lube charts they recommend SAE 90 EP for the differentials. I would like to know what Wes's opinion about this.
Zoli

hillbilly21 · Post by **hillbilly21** » Wed Dec 03, 2008 5:30 am

I just put in 85-90 Rotella in MINE yesterday

2 1/2 qts in each axle

tranny 1 qt

transfer case 3 pts

Post by **wesk** » Wed Dec 03, 2008 11:13 am

EP is Extra pressure and is a requirement of Hypoid type axles ring and pinions. The jeep has the hypoid type axle gears. The EP is not needed for the tranny/transfer.

GPA · Post by **GPA** » Wed Dec 03, 2008 12:41 pm

Yes Wes, but the plates on the Jeeps and the Army issued manuals state SAE 90. Only some civilian Jeep material mentioned EP oil for the diffs and they use very similar transmissions and differentials. The ratios are different. I thought you may know the reason.

Post by **wesk** » Wed Dec 03, 2008 10:30 pm

They say a little more than that. They say Gear Oil, Universal which from a discussion long ago was to the US Army all EP rated.

GPA · Post by **GPA** » Thu Dec 04, 2008 5:16 am

Hi,
So they recommended the Universal Gear Oil for both the transmission/transfercase and the differentials, but really only the diffs needed the gear oil wich contained EP additive. They did this because they did not want to carry or stock one more type of oil?
If we change the gear oils we have to put SAE 90 in transm. and SAE 90EP in the diffs?
Zoli

Post by **wesk** » Thu Dec 04, 2008 8:52 am

Yes. The EP will not hurt the tranny/transfer but the extra cost is not needed.

GPA · Post by **GPA** » Fri Dec 05, 2008 12:13 am

Thanks Wes.

pockers · Post by **pockers** » Thu Mar 19, 2009 10:09 am

Hi

can any one tell me if european Hypoid Gear oil EP 80W90 would be suitable for m38a1 gear box &/or diffs?
(as i have a quantity of this already)

others available to me are 75w/80 & 75w/90

any ideas what would best suit?

many thanks

Post by **wesk** » Thu Mar 19, 2009 9:10 pm

I see no harm using the semi-synthetic multi-viscocity EP oils so long as you use the correct grade for your climate. The only issue I take with the multi-viscocity oils is they are thinner when cool and when a vehicle is stored for long periods the thinner oil will drip off the parts more quickly leaving bare steel to corrode.

pockers · Post by **pockers** » Fri Mar 20, 2009 1:49 pm

Many thanks for swift reply

roll on the summer

fantastic web site!