1991 MB Differential with 206k miles - HPL Differential Life Cleaner Test (with pics)

[JHZR2]

My second 1991 MB 350SD with 206k miles has been getting all new fluids. My 10yo has been helping me do it all which has been great. Today it was the differential, which got @High Performance Lubricants differential life cleaner. Mine are “prototype” bottles from an early batch which Dave provided to me because I had noted how horribly foul the front differential on my brother’s 1996 Toyota FJZ80 land cruiser was. It too will get the treatment, we just haven’t had time together to do it, plus winter…

I may have a record of the last service, and I’ll look at some point. The fluid came out reasonably clean and clear.

I used a borescope to take photos of the interior. There does seem to be some deposits on the gears and in the case, though for the most part it’s clean.

I used the recommended 1:5 ratio with Supertech 80w-90 that I had on hand. It seems like fine enough fluid for these old diffs on these heavy but low powered cars. The differential holds about 1.3 quarts.

I’m interested to see if it cleans and disperses the residues from the drain plug. The plug came out looking blackish, but there was a similar light brown layer that nomwiping could get off.

Ill plan to drive with this maybe a few thousand miles, which will take a while, then report back. And ditto for some of my other cars and trucks…

 

[JHZR2]

Here’s the drain plug residue, which looked the same after wiping, a bumpy residue, just light brown instead of the black seen here:

 

[Trav]

Tooth wear looks good, it doesn't look like there is much of anything to clean.

 

[dnewton3]

What the difference between this product and the engine cleaner? Did Dave give you any indications as to what might set the two apart?

 

[JHZR2]

Tooth wear looks good, it doesn't look like there is much of anything to clean.

I agree. It’s pretty clean in there. Surprisingly so.

But we will see what we get…

 

[Marcozi]

Old school German engineering!

 

[wpod]

Did you do beform and after pics? How can we tell if the product actually cleaned? The front differentials in
my 4 wheelers over the decades usually lookl worst than the rears.

 

[JHZR2]

Did you do beform and after pics? How can we tell if the product actually cleaned? The front differentials in
my 4 wheelers over the decades usually lookl worst than the rears.

This was the starting pictures. The fluid was slightly murky, and I could see the same sort of coloration on the gears. The plug had a lot of junk on it, and there were signs in some places of dark buildup. Not much overall though. I was surprised how clean this diff was for 206k miles. The unit in my 300sd was much darker. But Im not keeping that car Long term.

 

[JHZR2]

What the difference between this product and the engine cleaner? Did Dave give you any indications as to what might set the two apart?

Not that I recall, Dave @High Performance Lubricants will need to weigh in on that. The retail product says it has high solvency but is gentle on elastomers. And to check it every so often for cleanliness.

 

[Revving2Redline]

Not that I recall, Dave @High Performance Lubricants will need to weigh in on that. The retail product says it has high solvency but is gentle on elastomers. And to check it every so often for cleanliness.

probably the weight of the cleaner. You wouldn't want a 30 weight viscosity in a gear lube I imagine.

 

[JHZR2]

probably the weight of the cleaner. You wouldn't want a 30 weight viscosity in a gear lube I imagine.

Check the viscosity chart:

A 30wt oil is like an 85w gear oil.

 

[Revving2Redline]

Check the viscosity chart:

View attachment 171477
A 30wt oil is like an 85w gear oil.

Hey! I always sway to the side of never guessing on an important part of a vehicle. Thank you for posting this. I humbly admit I didn't know.

 

[andyd]

Ignorance is bliss. I just learned a bunch. I had 5 Grand Wagoneer's over 20 yrs. I cant remember ever checking the front pumpkins for gear oil. Doh !

 

[4WD]

Ignorance is bliss. I just learned a bunch. I had 5 Grand Wagoneer's over 20 yrs. I cant remember ever checking the front pumpkins for gear oil. Doh !

I’m pretty over the top - all FF drive-line fluids done by 20k …
Like to clean loaded magnets and get them back to work …

 

[02SE]

Mine are “prototype” bottles from an early batch which Dave provided to me because I had noted how horribly foul the front differential on my brother’s 1996 Toyota FJZ80 land cruiser was. It too will get the treatment, we just haven’t had time together to do it, plus winter…

FWIW, I had a '95 FZJ80 with locking front and rear diffs, back in '95. I did the first service on it's axles. Even at only 4k miles, the gear oil in the front diff was the nastiest gear oil I can recall encountering. After the initial change, it never looked or smelled that bad again, in the five years I owned it.