ACDelco 75W-90 Syn Axle Lube, 13.7k mi OCI, 34k mi

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All mileage is in kilometers not miles. Switched to Red Line 75W90 GL-5 Gear Oil.

The previous fill was: "SAE 75W-90 Synthetic Axle Lubricant (GM Part No. 89021677, in Canada 89021678)" (quoted from manual)

Should I follow the recommended short OCI for the LSD?

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Originally Posted By: NMBurb02
Do you track this car?


Not on that OCI actually, since it was swapped in after my one and only track event last year, and swapped out before the first one this year.
 
So this was a 75W-90 that thickened to a 75W-140 viscosity or was it a 75W-140 oil? I cannot tell from the text. If it was a 75W-140, I would not drop it to a 75W-90 and if it was a 75W-90, I would increase to a 75W-110 or a 75W-140.
 
Originally Posted By: Emperors6
It was a 75W90 that thickened. Trying Red Line 75W90 to see if that also thickens.


Oh nooo ..... any xxW90 would not do with your applications, even if it's factory recommended.
shocked.gif


I would go thicker ... xxW110 or xxW140.
 
Originally Posted By: Emperors6
Are you saying that because a particular formulation thickened?
No, because a 75W-90 should not thicken to a 75W-140 viscosity under normal conditions. The oil is heavily oxidized (at least it seems so). If it were mine, I would switch to a heavier oil and a synthetic such as Amsoil.
 
Originally Posted By: zeng
Originally Posted By: Emperors6
It was a 75W90 that thickened. Trying Red Line 75W90 to see if that also thickens.


Oh nooo ..... any xxW90 would not do with your applications, even if it's factory recommended.
shocked.gif


I would go thicker ... xxW110 or xxW140.


What do you think of the Red Line Shock Proof Heavy? My mechanic has been pushing for that. Would that be good an the track? Would it also be good for winter use?
 
Originally Posted By: Emperors6
Originally Posted By: zeng
Originally Posted By: Emperors6
It was a 75W90 that thickened. Trying Red Line 75W90 to see if that also thickens.

Oh nooo ..... any xxW90 would not do with your applications, even if it's factory recommended.
shocked.gif

I would go thicker ... xxW110 or xxW140.

What do you think of the Red Line Shock Proof Heavy? My mechanic has been pushing for that. Would that be good an the track? Would it also be good for winter use?


Without data like KV@40*C and KV@100*C for RL Shock Proof Heavy/Lightweight as track oils, unfortunately I'm unable to comment with certainty as to its winter use and general suitability for your Cadillac.

However from amongst RL gear oil products of known viscometrics for track use (as well as general use), I would personally prefer :
a )RL 80W-140 GL5 (KV@40*C=227 cSt/ KV@100*C=26 cSt), or
b )RL 75W-140 GL5 (KV@40*C=192 cSt/ KV@100*C=27.8 cSt), to
c )RL 75W-110 GL5 (KV@40*C=131 cSt/ KV@100*C=20.9 cSt.

Under identical operating conditions, I'm afraid RL 75W-90 (KV@40*C=112 cSt/ KV@100*C=16.1 cSt)as originally intended, may not work for your case.

Just my $0.02.
blush.gif
 
Originally Posted By: Emperors6
zeng, would you also give the same recommendations for track use?


Yes,(a) and(b) above are for track use AND daily driver, aggressive or otherwise.

I won't be comfortable with (c) in track use in terms of components protection , moderate daily driving should be ok, I suppose.

Btw, was your used oil sample color dark black or moderate brown?
 
I see, zeng. Thanks.

I have the Red Line 75W90 in and I'm going to have four upcoming track weekends this summer. Should I swap it out right now? I put it in when the UOA in this post was done.

I didn't take a look at the colour, but there was some film residue in the plastic bag the mechanic gave me to hold the sample bottle and it looked much darker than brown.
 
Originally Posted By: Emperors6
I see, zeng. Thanks.

I have the Red Line 75W90 in and I'm going to have four upcoming track weekends this summer. Should I swap it out right now? I put it in when the UOA in this post was done.

I didn't take a look at the colour, but there was some film residue in the plastic bag the mechanic gave me to hold the sample bottle and it looked much darker than brown.


That's your call really.

Using the above AC Delco @13.7k mi as a base line, your new RL 75W90 should be fine up to say, 7-9k mi of DD use.
I would strongly recommend swapping out before upcoming track use.
blush.gif
 
I see. That does concern me, but I want to get a baseline before going to the highest viscosity since Dave at Red Line said it should be fine. I'm going to keep it in for 6mo / 6k mi / 10 track days. Hopefully, I won't need a new diff in a few months.
 
75w110 = more cushion for the pushing.

Of course, if you are just slamming the gas pedal upon corner exit and letting the components take a beating maybe do all you can to hold everything together!
 
Originally Posted By: Emperors6
I see. That does concern me, but I want to get a baseline before going to the highest viscosity since Dave at Red Line said it should be fine. I'm going to keep it in for 6mo / 6k mi / 10 track days. Hopefully, I won't need a new diff in a few months.


Meanwhile check its temperature with an IR gun or palm/finger touch in seconds.
 
I have a crystal thermometer that retains the maximum temperature it encounters. It's a little sticker that attaches to the diff housing. The hottest it got last time was 250F.
 
Originally Posted By: Emperors6
I have a crystal thermometer that retains the maximum temperature it encounters. It's a little sticker that attaches to the diff housing. The hottest it got last time was 250F.


Oh jeez.... get the xhell out of the differentials ......
You gonna to mess up with this 75W90!
cry.gif
 
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