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I'll be pulling my trans to replace my clutch, my question is....Does my Luv really take 10/30 motor oil instead of trans fluid. I called a auto parts store today to check on some other things and it just seemed odd, Any thoughts would be greatly appreciated!

Isuzu manual trannies (& t-cases) use motor oil, the best viscosity depends on the ambient temperature, same as the engine. 10w-30 works for the temperature range most trucks are used in.

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'78 Chevy LUV,1.9,4sp,headers,31's,SAS Dana 30,Dana 20,SOA rear w/Aussie Locker, rough body, bought new 12/4/78.
'87 Trooper,2.3,5sp,headers,31's,ball joint flip & spacer,Aussie Locker rear,Superwinch hubs,brush guard w/5.5K winch,more to come.

When I replaced my clutch, I changed my tranny oil, but I used 80w gear oil

little-blue
you need to get that gear lube out of your tranny ASAP, replace it with engine oil per factory specs. There are sealed bearings & close tolerances within the tranny that the gear lube will not penetrate properly. Gear lube use is a known cause of failure for Isuzu trannies, it's just too thick to keep everything lubed.

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'78 Chevy LUV,1.9,4sp,headers,31's,SAS Dana 30,Dana 20,SOA rear w/Aussie Locker, rough body, bought new 12/4/78.
'87 Trooper,2.3,5sp,headers,31's,ball joint flip & spacer,Aussie Locker rear,Superwinch hubs,brush guard w/5.5K winch,more to come.

Thanks

Common problem, and a common mistake. I've had a couple trucks that had gear lube (80-90W etc) in them when I got the truck and they didn't really seem to suffer much from having it in there, but I swapped it out quick. The bearings in the Isuzu manual transmissions are designed to swim in motor oil, and gear lube is too thick to always penetrate in to where it is needed, at least not right away.

I'd recommend you go for a good drive, 20 miles plus, then dump that stuff out. It flows much better hot and more of it will drain out. Then change the fluid again fairly soon.

There are companies that make manual transmission fluid, basically motor oil of the correct weight with a mix of detergents and additives that are suited to transmission use. I've never tried any, engine oil has always worked well.

Just as an added note, gear oil in the trans is probably enough to drop gas mileage by a point or two at least.

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95 Isuzu Trooper Daily Driver
86 Isuzu Trooper reliable backup
77 LUV 2wd stock beltway blaster (resting)
79 4x4 LUV project: 2.6L, 5spd, 31s (eventually)

MEPR: Man, my 4x4 makes all other LUVs look good

Just read this and went out and changed my fluid out, definitely smelled gear oil in it

I just had the clutch go out on my '77 two weeks ago. I got lucky and went to a friends garage who had a lift for a couple of hot rods he has. We moved them out and I got started with help of another buddy and two of us got it done in about 5 hours. Drives like a champ now. Be sure to remember to 'tie or wire' off the clutch slave cylinder or the piston will fall out due to the above clutch fluid pressure. I have 'learned' this lesson several times. It looks like it will stay in the cylinder housing---but it doesn't. Put some kind of a baggie over the end of the tranny to catch any oil that spills out of the rear housing. I usually use a rubber band to hold it in place. Check the u-joints while you're there. The two top bell housing bolts are a real pain and I use a couple of long 3/8" extensions and a 45 degree swivel with a deep socket to reach them. They can be reached from the top side with a box 'ratchet' wrench to loosen them first but it is slow going to remove them with that type of wrench. I buy 'lifetime' parts for my truck and have had it for so long that it rarely costs for new parts.

Sorry guys....I didn't check the date of the original post. Guess all my stuff is too late.......