I just changed my rear end gear oil. Checker auto told me I only needed 3 quarts. Is that enough?

How much motor oil does my truck hold? 12 quarts?

I have a 2005 Ram 2500 Diesel (auto transmission). How do I know which rear end I have?

Thanks,
Jason

 

Fill the diff to the bottom of the fill hole. When it starts to come back out, it's full.

Yes, 12 qts.

There's usually a sticker uner the hood or in the glove box that tells you what options are installed.

Or, put the rear on jack stand. With the trans in neutral, turn the drive shaft by hand 10 turns. Count how many times the tire rotate in those 10 turns. Write as a ratio, and then divide by 10.

For example. The drive shaft turns 10 times, the tire turns 35.5 times = 35.5:10. divide by 10 = 3.55:1.

 

Slight typo there: For 3.55 gearing the drive shaft makes 3.55 revs for each 1 rev of the tire.

 

You wil need at least 4 qts for your rear diff. Maybe even a bit more, I can't remember for sure.

Your rear diff will most likely be a 3.73. Only other factory option is 4.10.

 

.bob

I think the ratio is figured this way.

If you have a 3.73 to one ratio and you turn the driveshaft 10 revolutions, the rear wheels will turn 10 divided by 3.73 = 2.68 turns.

 

Mine took around 4.5 quarts of gear lube, yes and 12 quarts of engine oil, mine takes about 11.75 quarts with a filter, always fill the filter before putting back on.

 

True, but why mess with spinning the driveshaft 10 times?

A 3.73 means the driveshaft turns 3.73 times for each wheel rotation.

 

If you have the inspection cover off you can count the number of teeth on the gears.

41 Ring/11 Pinion = 3.73
41 Ring/12 Pinion = 3.42

I'm not sure of the other ratios, but just divide the number on the ring by the number on the pinion.

 

Exactly. I was just responding to the previous calcs suggested by .boB.

 

Because you get better accuracy. Probably not that important, but I tend to do a little overkill on this sort of thing.

And, as noted above, I had it backwards.

 

You'll need just under 4 qts for the rear diff, and just under 3 for the front. Fill it to the line on the outside of the diff cover that is under the fill hole. The factory says you can risk blowing out seals if you over fill it.

You'll need 12 qts for the engine, (including the filter)

Check the glove box, if it doesn't say it there then jack the truck up and rotate one rear wheel while watching the drive shaft. Count how many times the drive shaft turns with 1 full rotation of the wheel. It'll either be 3.73's or 4.10's. Another way to tell, (if you have to stock size tires that is), is if you have 3.73 you'll be at about 1900 at 70 and w/ 4.10's you'll be at about 2100/2150 at 70.