Rear differential refill - 91Q

Post by **paintwgn** » Tue Mar 18, 2003 9:02 am

Decided to change the oil in the rear last weekend.No problem reaching the drain plug from the rear with a 1/2" drive. Same with the fill plug. But trying to get the Mobil 1 75w-90 into the differential from behind and beneath the car was next to impossible. Wound up jacking up the drivers side rear and taking off the tire.Then my assortment of funnels and tubes worked fine. Even warmed the oil first to make it easier to squeeze/pour.

Post by **AZhitman** » Tue Mar 18, 2003 9:02 am

I just attached a length of fuel line to the top of the Mobil 1 container, tucked the bottle up between the axle and the exhaust and squeezed. Worked great and no need to pull a wheel.

Either way, it's done, right!

Post by **911/Q45** » Tue Mar 18, 2003 9:02 am

I transferred my gear lube to a smaller squeeze bottle and fit that in the space easily. A couple refills and done with no mess. You can bet I saved that bottle!

Post by **nuQ** » Tue Mar 18, 2003 9:02 am

thanks paintwgn!!! you read my mind. i was just about to post a thread about changing the differential fluid, or more specifically what brand. how much should i buy to do the job? thanks guys, jeff

Post by **PalmerWMD** » Tue Mar 18, 2003 9:02 am

Tho I am not positive about the #, I am positive that 2 of the standard size bottles were clearly plenty enough for a Q diff.

Most here prefer the MOBIL1 GL-5 gear lube, though other good brands clearly exist.

Fred..

Post by **paintwgn** » Tue Mar 18, 2003 9:02 am

Jeff,Differential takes about 1 1/2 quarts, so 2 quarts is more than enough. Interestingly, when I removed the drain plug, the magnet was covered with a black sludge-like coating(110,000 mi.) The oil that ran out, however, was still clear-like new motor oil. Looks like the magnet works real well in trapping metallic particles.

Post by **DAEDALUS** » Tue Mar 18, 2003 9:02 am

The '90 takes 1.5L. If you ever change you fuel pump, save the old one for transferring fluids.

Post by **nuQ** » Tue Mar 18, 2003 9:02 am

is there any kind of indication that the diff. is full(full line where you put the fluid in?) or do you just go by 1 1/2 bottles of lube? thanks again guys, jeff

Post by **DAEDALUS** » Tue Mar 18, 2003 9:02 am

The manual doesn't state it explicitly, but it *looks* like a full differential would be just about to overflow the fill plug hole.

Post by **AZhitman** » Tue Mar 18, 2003 9:02 am

Buy 2 bottles and fill it til it runs out the filler opening.

Post by **landtodd** » Tue Mar 18, 2003 9:02 am

Good and often-overlooked preventive maintenance to change the diff lube. Spend $10 to do as much as you can to protect a $2000 part? Yeah, those are odds I'll take!

An Infiniti is the *only* car I've ever laid hands on that actually lost a differential. Okay, it was an M30 (remember those? Sorry to hear it), but Dennis said they've seen a rash or two of bad Q45 diffs at T3 in the last couple of years.

Enough vinyl tube, and you can put the quart bottle just about anywhere you want it. Refill can be a mess -- don't sqeeze too hard on the bottle. A helper helps a lot. I used the Valvolene full syth. No opinion about what's best, but Valv always seems to be near the top of the list for all kinds of fluids.

Did this on my birthday last year, getting tires this year.

Post by **szh** » Tue Mar 18, 2003 9:02 am

paintwgn wrote:Jeff,Differential takes about 1 1/2 quarts, so 2 quarts is more than enough. Interestingly, when I removed the drain plug, the magnet was covered with a black sludge-like coating(110,000 mi.) The oil that ran out, however, was still clear-like new motor oil. Looks like the magnet works real well in trapping metallic particles.

My dumb questions: I assume the magnet is cleanable? Is it attached to the drain plug or just inside somewhere?

Z

Post by **Mayhem_J30** » Tue Mar 18, 2003 9:02 am

szhosain wrote:My dumb questions: I assume the magnet is cleanable? Is it attached to the drain plug or just inside somewhere?

Z

You're correct. The magnet is attached to the top of the drain plug. You'll see a build up of black slime and it can just be wiped off.Then like AZ said, just fill it to it start to flow out of the fill hole.Make sure you have a bucket underneath when you drain it. Don't want to get it on ya...stinky. :puke

Post by **paintwgn** » Tue Mar 18, 2003 9:02 am

The magnet is attached to the plug. It looks like a large rubber washer. Just wipe it off.

Post by **AZhitman** » Tue Mar 18, 2003 9:02 am

Mine had almost no funk on it whatsoever.

I grenaded a rearend in my 68 GranSport at the track. Third run of the night, running 15.6's consistently in a 4000 lb car, and it just EXPLODED. Ruined the lane for the night. Needless to say I was unpopular that evening.

Post by **natsoundup** » Tue Mar 18, 2003 9:02 am

Whoops....my 90Q has 151k on it.... never touched the rear differential.....

I suppose I should get it changed the next time I get the oil done....

Post by **nuQ** » Tue Mar 18, 2003 9:02 am

here's an even dumber question..is there two plugs, one for drain one for fill. if i remove one and drain with that(assume magnet is on that one), is there an upper plug to fill. ps-first time if you haven't guessed! jeff

Post by **DAEDALUS** » Tue Mar 18, 2003 9:02 am

Yes, one on the bottom and one above. Natsoundup, I don't know if "change" is the right term at 151k. Maybe refill is a better term.

Post by **911/Q45** » Tue Mar 18, 2003 9:02 am

Be sure and return to this thread and let us know what comes out when you change it!

Rear differential refill - 91Q

Rear differential refill - 91Q

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