Castrol's gear lubricants and ATF

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Are there such things as "Best Oils"?

Well after many years in this business I can only allude to "in service" performance rather than Specification Sheet numbers and postulations over base oils and additive package formulations

Many years ago when using RoadRanger-RR-heavy truck gearboxes it was a requirement to "re-race" the box and replace selector components at regular intervals. A debate at the time raged over which oil to use, a SAE 90 GL5 gear oil or an SAE 50 engine oil. The maker recommended SAE50, but truck operators used both and with almost equal results

The main RR wear indicators were;
a) "noise" for the bearings
b) gear lever "slop" and mis-selection for the selector mechanism. Most selector wear was caused by the Driver's -collectively- habit of resting their hand on the knob of the 4ft long gearlever for hours on end! This multiplies the load on the selector components which are usually free of load until used for gear selection

Castrol's Synthetic Gear oils and synthetic ATF

A - I commenced using Castrol's Syndrive 50E in RR gearboxes in 1992
B - As well I commenced using Castrol's excellent Syntrax, either 90w-140 and latterly 75w-90, in Rockwell & Eaton axles at the same time
C - I started to use Castrol's Syntrans a GL4 too in various vehicles in 1992, and when Transmax Z ATF appeared commenced using it too

Over the last 12 years I can report a tale of success;

1 - we have never re-raced a RR gearbox since 1992*
2 - we have never replaced any RR oil seals since 1992*
3 - we have never replaced any selector components since 1992*
4 - we have never had a differential failure since 1992*
5 - we have replaced the odd wheel hub oil seal at around 500k - usually a regular job at
IN EACH CASE THE GEARBOX AND DIFF LUBRICANT WAS CHANGED FROM THE MINERAL FACTORY FILL OIL DURING THE FIRST 3K on average

IN EACH CASE THE OIL WAS NEVER CHANGED AGAIN* - SOME RANDOM UOA's WERE TAKEN

* Up until vehicle disposal at 700k

Admittedly RR's technology has improved since 1992 as well

We now use Mobil SHC50 and SHC 75-90 in some vehicles too

It should be noted that the operating range of ambient temperature is from -10C to 50C

I hope this is of interest

Regards
 
Doug, I know you posted this great info some time ago but I would like to ask you a few questions.

Can you tell me what the gear oil capacity for the gearboxes is?
How many years do you usually have gear oil in service?
You run gear oil for 700k km, not miles. Is this correct?
Have you noticed any difference in performance, fuel economy, reliability, or any other factors between 75W-90 and 75W/80W-140 GL-5 gear oils?
Have you tried any other synthetic gear oils from Redline, Mobil, Shell, or any other major brands?
What's your experience with Transmax Z? It is not available here in the US. I heard of many good things about it and nothing bad. I found data sheet online and it looks excellent. Some even say that it is the best ATF around. Have you tried any other synthetic ATFs like Redline, Mobil, or others?

Thank you,
 
Hi,
Titanium_alloy - I hope the following is of interest;
Gearbox capacity - 15 to 18 litres depending on vehicle configuration

Diff capacity - front and rear diffs vary due to interaxle drive but 15 to 20 litres

The oil stays in for about 700k miles

The only noticeable difference with the lighter diff oil is the significant reduction in operating temperature. As "HEYJAY" ( Jerry ) and I know very well there are too many variables to accurately state a case for better economy due to the lubricant

I have tried Mobil synthetic gear lubricants and they are performing on a par with Castrol

Transmax Z has a great reputation here. Both in drag racing and in other applications. I believe it is the best ATF available regardless of price
I have used both Mobil and Shell ATFs and settled on the "Z"

Steve S - Filters are fitted to the front diff. This diff unit also contains the interaxle diff
and is under some "stress". These filters are generic - at least for me

Our RoadRanger gearboxes also have a remote mounted filter at the front of the vehicle in the air flow. This filter is nothing special and we use Fram ( if you hit a Kangaroo they may danmage the filter even though they are shielded ) and each Driver carries a spare

Thanks for your interest
Regards
Doug
 
Great information. Thank you very much.
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