Sludge on Differential. Drain Plug....Go Thicker?.

[JSRT4]

I dumped my differential fluid after about one year's use and 5k miles, I found quite a bit of black/brown sludge on the drain plug. The fluid used was Amsoil 75w-110, recommended fluid by manufacturer was SAE90. I don't know if it was from this fluid or just cleansing of old fluids by the Amsoil.

Would it be appropriate to use a 75w140 viscosity Amsoil fluid as a second run to see if things improve ?. I've sent a used oil analysis of the 75w110 but I won't have it back for a few weeks. I'll do a used oil analysis of the 75w140 in about one year's time. My differential only holds .8 quarts, so not very much capacity, I was thinking the 75w140 might help to lower diff. temps. The car is only driven in summer conditions.

Would a thicker fluid like 75w140 lower diff. temps over a 75w110 using the same fluid manufacturer (Amsoil SVG)?, I don't think that I want to go any thinner than 75w110. This is on a 2002 Honda S2000 differential. Thanks for any replies.

 

[jstutz]

I believe thinner fluids tend to run cooler as they conduct heat better and transfer it away from the gears. I dont know if this is true under all conditions though.

 

[JSRT4]

thanks for the reply on this, I know that applies to engine oil theory where fluid is pumped over and through parts, is it the same for differentials ?

 

[Colt45ws]

Are you sure its sludge? Some plugs have a magnet and will collect metal particles. When combined with gear lube it does have that 'sludge' consistency.

 

[The motor guy]

It's a bunch of tiny metal particles. It should look like a grey paste.

 

[JSRT4]

yeah I dumped the diff. fluid when I first got the car and it had a bit of grey metallic paste on the drain plug which is magnetic. So one year later 5k miles and Amsoil 75w110 I drain it and it has a thick black paste on the drain plug, a totally different colour which is much darker than the typical grey paste and somewhat thinner consistency, kind of like grease. It's baffling to me, the car is driven very easy, no hard use or racing, pretty much short distance city driving mostly. I hope to get my used oil analysis results very soon to see if it is wear related.

 

[Pablo]

You are looking at the cleanup of the factory fill FeS complex varnish. You'll probably have it happen one more time with a lesser amount, but for sure just stick with the 75W-110.

I'm sure you will have elevated Fe in the UOA. You maybe shocked by the number!

 

[JSRT4]

thanks Pablo, I'll see how the numbers look, thanks for the heads up on possible Fe numbers.

Do you think there is anything wrong with running Amsoil SVG 75w140 ?, I may have over-reacted and I've put that into the diff. at the present time. Should I go back to 75w110 ? It's an easy change either way, less than one quart. Thanks for any opinion on this.

 

[Pablo]

Thicker may not be prescribed. Maybe run it for a short while and go back to the 110. A good flush!

 

[JSRT4]

Originally Posted By: Pablo
Thicker may not be prescribed. Maybe run it for a short while and go back to the 110. A good flush!



Okay, will do, it will be a good flush for sure. thanks again.

 

[INDYMAC]

I think you are just seeing some cleaning going on. I'm not sure how telling the UOA will be, since it won't detect sludge. Using 75W-140 shouldn't be a problem. I've considered going to it a few times here in Texas to help with gear whine on hot days. If you are worried about it, just do a short OCI and go back to 75W-110 like Pablo recommends. If that's what you decide to do, consider adding 2 ozs of ARX to help with the cleaning and condition the seals. I did that on my last fill in my S2000. Paste on the drain plug has not been a problem. But since the car is almost 7 years old I thought the seals could use some cleaning and rejuvenating.

 

[JSRT4]

Originally Posted By: INDYMAC
I think you are just seeing some cleaning going on. I'm not sure how telling the UOA will be, since it won't detect sludge. Using 75W-140 shouldn't be a problem. I've considered going to it a few times here in Texas to help with gear whine on hot days. If you are worried about it, just do a short OCI and go back to 75W-110 like Pablo recommends. If that's what you decide to do, consider adding 2 ozs of ARX to help with the cleaning and condition the seals. I did that on my last fill in my S2000. Paste on the drain plug has not been a problem. But since the car is almost 7 years old I thought the seals could use some cleaning and rejuvenating.


As always Indymac, thank you for your helpful replies. I took the car out for a drive today and it felt more sluggish for some reason to me. All I can think of is the thicker diff fluid, but I never thought .8 quarts of a thicker fluid could make this car more sluggish, I know it was much harder to pump into the diff than my 75w110 was, my arms felt the difference

 

[INDYMAC]

I would expect the 140 to feel a little "sluggish" at first, but will probably be negligible once the fluid is hot.

I can relate to wearing your arm out while hand pumping. Let the gear oil sit in the sun for awhile before pumping. Or let the bottle sit in some hot tap water for 15 minutes. The S2000 isn't too bad. At least you can see the light at the end of the tunnel. I almost cried the last time I hand pumped 3.5 qts of LE1605 (SAE 110) into my Tundra on a cold day!

 

[mechtech2]

I see Canada.
I would not go to a 140 .
You legally need 3 hard factual reason to do so.

 

[Doug Hillary]

Hi,
JSRT$ - It all sounds (appears) quite normal IMO. used oil analysis on transmission fluids can be a little overwhelming for those that see engine oil used oil analysis

Synthetic fluids tend to drop operating temps in diffs by up to 20C. IMO many diffs in cars used "normallY run very cool and rarely go above about 90C

The manufacturer specifies a SAE90 fluid? - then, a 75W-90 would be my choice especially where a low ambient is typical

 

[JSRT4]

Thanks guys, yeah the low temp consideration isn't too important as I store it for winter, it is a 3 season car only.

The s2000 spec on the diff was SAE90 set back in 1999 when the vehicle was developed, thus the old SAE90 which compares nicely to today's 75w110. I may just go back to 75w110 once the used oil analysis data comes back, I think the 75140 is a tad thick. Thanks for the helpful input .