gear oil rear end

[geirws]

does anyone know if it's necessary to change gear oil in the rear end of my 1977 argosy motorhome as often as the owners manual says? every 4 months or 12,000 miles?????

[87MH]

Originally Posted by geirws

does anyone know if it's necessary to change gear oil in the rear end of my 1977 argosy motorhome as often as the owners manual says? every 4 months or 12,000 miles?????

I seriously doubt if many (or any) P-30 chassis' get their rear end fluid changed every 4 months. The Motor Home Chassis Service Guide hints that the proper service might be to change the fluid every 4th motor oil change.

That would work out to a bit more than once a year with my level of driving. I don't know if it would be wise to let it go longer than that, although it was right at a year when I changed mine ( more accurately, - had it changed), and the lube experienced no visible degradation in the year and two months that it was in the rear end. Of course, if you see damage or bad fluid, it may already be too late.

The differential on the 345 is a bugger to get to - the tag axel is right in the way.

[swebster]

Mine is [over]due! Does anyone know the recommended fluid for the diff and where to get it (AutoZone, NAPA?)

I"ll do it this week!

[aviontt]

80/90w Gear oil any auto parts store....

[74Argosy24MH]

Get a gasket (or rtv sealer), pull the cover and clean the bottom of the housing. There should be a magnet on the cover, it will have metal on it. OK as long as it is not excessive and chunky. Autozone here has dino and Valvoline synthetic and semi synthetic.

John

[87MH]

Originally Posted by 74Argosy24MH

Get a gasket (or rtv sealer), pull the cover and clean the bottom of the housing. There should be a magnet on the cover, it will have metal on it. OK as long as it is not excessive and chunky. Autozone here has dino and Valvoline synthetic and semi synthetic.

John

There is no drain plug on the differential. It's important to actually pull the rear cover and clean and inspect the bottom of the differential for metal filings and other debris. You can visually inspect the outer edges of the gears at the same time. Look for chips and galling.

For as little fluid as it takes to fill (two or three quarts) this might be a good application for a true synthetic.

Don't want to start a Synthetic/Blend/Dino-oil discussion, but true synthetics have a lot to offer over the Dino multi-grade.

Personally, I use Dino, because of the Synthetic cost and the fact that I'm pretty anal about changing the oil on schedule or before, but for a use where the oil will not be changed as often (rear end and tranny) the chemical benefits may well justify the costs.

For what it's worth, when the tranny in the 345 was rebuilt in May of 2004, the rebuild shop recommended waiting a year (12,000 miles) before replacing the (new, existing) Dino oil with Synthetic. Don't know the reason, just what the shop recommended. I also installed a drain plug in the tranny pan at the rebuild, right now I plan to switch to Synthetic next spring.

As far as the differential, I may switch to synthetic on the next service inspection, but there does not seem to be a high failure rate on this piece of equipment, even loaded as heavily as they are in the larger MoHo’s, most of which have run Dino their entire lives. With almost 80,000 miles on the engine (and an increasing thirst for oil) I will continue to run Dino-oil in the engine. The engine is using a quart about every 500 miles, but there is no visual indication of impending failure in the engine (no leaks, no oil in the carb, no indication of oil in the exhaust, no indication of a blown head gasket).

[74Argosy24MH]

Originally Posted by 87MH

For what it's worth, when the tranny in the 345 was rebuilt in May of 2004, the rebuild shop recommended waiting a year (12,000 miles) before replacing the (new, existing) Dino oil with Synthetic. Don't know the reason, just what the shop recommended. I also installed a drain plug in the tranny pan at the rebuild, right now I plan to switch to Synthetic next spring.

Synthetic is too slippery, the clutches and steels will glaze.

Synthetic is great for differentials on vehicles like these. Very tacky, more protection after long periods sitting. Differentials are probably the most abused part of a vehicle. I bet a lot go to the junkyard with the same oil as the factory put in.

John

[swebster]

OK...going to get a gasket and oil today. I see a listing at AutZone Online for two gaskets for the 86 P30, 454; one for a Dana rear end and the other for a Non-Dana. Does anyone know which kind we have back there?

[74Argosy24MH]

Mine has a 10 1/2" GM, 14 bolt cover, sort of round but flat sided if that makes any sense. RTV will work just as well (clean and dry all the surfaces) if you want to hedge you bet.

John

[geirws]

thanks to those who answered about changing gear oil in the rear end. Having it done today by the local GM dealer.