owners manual states rear diff lubed 4 life

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FiremarshalRob

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Well, I thought I needed to change the diff fluid in my 2002 F150 2wd since I just turned 82K miles, but I read my owners manual and it states "your rear differential is lubricated with a synthetic lubricant and is considered lubricated for life. Only needs to be changed if the rear diff has been submerged water, a leak is suspected, or maintenance is required to the rear diff."

Well, none of the above have happened and I'm having no issues. Just thought it would be a good idea.

I guess I should leave well enough alone?
 
I tow with my truck maybe 3-4 times a year. And that is with my small trailer with either my lawnmower to the shop for maintenance or my 4 wheeler.

Never have hauled/towed a super heavy load, but maybe that doesn't matter.
 
Originally Posted By: FiremarshalRob
Well, I thought I needed to change the diff fluid in my 2002 F150 2wd since I just turned 82K miles, but I read my owners manual and it states "your rear differential is lubricated with a synthetic lubricant and is considered lubricated for life.


When your differential fails, it will officially be dead and the "lubricated for life" will be over by definition.

It would be a good idea to change it now and then determine from the condition of the lube when you should change it next. Unless you don't plan on keeping the truck much longer.
 
Originally Posted By: XS650
Originally Posted By: FiremarshalRob
Well, I thought I needed to change the diff fluid in my 2002 F150 2wd since I just turned 82K miles, but I read my owners manual and it states "your rear differential is lubricated with a synthetic lubricant and is considered lubricated for life.


When your differential fails, it will officially be dead and the "lubricated for life" will be over by definition.

It would be a good idea to change it now and then determine from the condition of the lube when you should change it next. Unless you don't plan on keeping the truck much longer.


That's the way I feel too. Just interesting that the OM states "considered lubricated for life."
Now if I can just find Redline 75w140 online! I can find the 80w140 all day long.
 
Last edited:
Originally Posted By: FiremarshalRob
.........but I read my owners manual and it states "your rear differential is lubricated with a synthetic lubricant and is considered lubricated for life. ..............


I think "lubricated for life" actually means "lubricated for life of the warranty"!

I think you would have been better off doing your first change at 5000-10000 miles, to remove all the ring and pinion wear products, but that is water under the bridge.

Go ahead and do a change now. Be prepared for some very dark oil to drain out of the rear end.
 
I'm going to tackle that and my ATF asap. I have unfortunately neglected the transmission and the diff, but I sure keep up with my oil and filter changes.

I'm thinking about Red line for the rear diff and Valvoline Mercon V fully synthetic for the transmission.

Sound good?
 
Since you've neglected your transmission and diff, I think it's the perfect opportunity to buy a bottle of Auto-RX. Pour half a bottle in the transmission, and half a bottle in the diff. Drive it 1000 miles and then do a complete flush of your transmission fluid with whatever you choose (AMSOIL, Schaeffers, Mobil 1, etc.). Just drain and refill your diff with the gear oil grade specified in your manual. I'm not a Redline fan, but use it if you wish. The top rated synthetic 75W-90 GL5 options seem to be AMSOIL SVG or Mobil 1. If I were going to use AMSOIL, I'd order their SVT 75W-110. I think that would be a great choice for Baton Rouge.
 
Most people never change their gear oil, until 80,000-150,000 miles, when the bearings fail, and scar the axle shafts, resulting in a $500-$1,000 repair bill.

Replace your gear oil. It is a cheap way to protect your truck.

Royal Purple is the least expensive fully synthetic gear oil, but Valvoline and Mobil 1 are the easiest to find.

As for the transmission, I'm a huge fan of Mobil 1 full synthetic Mercon V. It is easy to find, and lasts a long time.
 
My 2000 Explorer owners manual states to wait until 150K to change the dif oil. I changed it a couple of weeks ago for the first time (8 years and 114K later) and that old fluid was very clean looking. Just refilled with 80w-90 Valvoline conventional and now plan to change out every 2 years.
 
Hi,
I have had considerable experience in running two synthetic lubricants (Castrol & Mobil) in heavy trucks (US Class 8) out to 1m kms (620k m) OCIs or up to five years

Monitored by used oil analysis the lubricants still had a service life at the OC point

I never suffered any major component failures, very rarely a seal failure and no bearing failures

I always changed from the Factory fill mineral lubricant to a synthetic prior to 5kkms (3k m)

I believe that modern synthetic lubricants are easily able to be a fill for life (to first life overhaul) if they are kept free of contaminants. Monitoring via used oil analysis is a requirement for extended use IMHO
 
Last edited:
Originally Posted By: mechtech2
It IS lubed for life.
For EXTENDED life, change it.


I've always wondered "whose life, exactly?" It's easy for an OEM to say "if it's worn out, it's life is over!" As mechtech put it so well - "Oh! You want long life? Then CHANGE THE OIL dumb@ss!"

It just seems silly to me - "for life" is an empty phrase that sounds good but doesn't mean much.
 
kind of like saying a room could be any temperature and still be considered "room temperature".

I agree that "filled for life" is completely meaningless fluff.
 
Originally Posted By: Doug Hillary
Hi,
I have had considerable experience in running two synthetic lubricants (Castrol & Mobil) in heavy trucks (US Class 8) out to 1m kms (620k m) OCIs or up to five years

Monitored by used oil analysis the lubricants still had a service life at the OC point

I never suffered any major component failures, very rarely a seal failure and no bearing failures

I always changed from the Factory fill mineral lubricant to a synthetic prior to 5kkms (3k m)

I believe that modern synthetic lubricants are easily able to be a fill for life (to first life overhaul) if they are kept free of contaminants. Monitoring via used oil analysis is a requirement for extended use IMHO
Doug, I agree. To quote my post on a similar thread: Most of the gear oil used in "lubed for life" service is synthetic 75W-90 or 75W-140. Products of this type are approved for extended drain intervals up to 500,000 miles by manufacturers such as Eaton in heavy duty class 8 trucks. My guess is that they will perform quite well in passenger vehicles for their useful life. Mobil Delvac synthetic, for example, is the factory fill on synthetic spec'd Eaton rear diffs that are warranted for 500,000 mile drain intervals in class 8 applications: http://www.mobil.com/USA-English/Lubes/PDS/GLXXENPVLMOMobil1_Synthetic_Gear_Lubricant_LS_75W-90.asp
 
I have worked on plenty of rear axles that were factory filled "for life" with 75w90 or 75w140 synthetic. That didn't stop the bearings from wearing out and scarring the shafts.

That is why I always check out gear oil for RWD and and 4WD vehicles, and recommend replacement every 50,000 miles.
 
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