I realise there are way too many variables involved, including clearances, oil type, etc, but my question is relating to a situation where I feel that the specified viscosity is becoming too thin on +35*C days.
The shift quality is deteriorating at higher temperatures, becoming slower, where you can feel the synchro clutch and hub ride over each other and the dogs engage, which I don't get at lower ambients.
Can this be an indication that I'm also losing gear and bearing protection ?
The lube in question is Redline MTL (10.2cSt @ 100*C, VI 171) in a pressure lubricated Land Rover R380 gear box.
The factory fill is Texaco MTF 94 (10.5cSt @ 100*C, VI 190). Prior to using MTL, I used Castrol Syntrans (PAO/ester, 11.9 cSt @ 100*C, VI 183) This is a Euro Castrol, designed for extended drain, heavy vehicle transmissions in Europe (MAN, Volvo and MB. They use synchro boxes exclusively)
I had the same 'problem' with the Syntrans.
All these gear oils appear to be biased towards cold temperature performance, which I don't need. The lowest it has ever been in winter here is -7*C, and the shifting is flawless, but we are in the middle of summer now, and even though I don't live in a hot area, it has been over 40*C about 5 days already.
I'm going to mix some MT90/MTL 50/50, but am reluctant to go any heavier as the gear box does have an internal pump that supplies all the bearings through internal drillings.
I'm currently logging 'box/oil temperatures on a transfer pipe, with the highest reading so far being 65*C on a 32* day after 30km. I have to do a 320km trip tomorrow, (to get some more Redline
) so I can see how the temps evolve on some windy slow roads.
Any thoughts, Ladies and Gentlemen ?
Or am I worrying over nothing ?
Rick.
The shift quality is deteriorating at higher temperatures, becoming slower, where you can feel the synchro clutch and hub ride over each other and the dogs engage, which I don't get at lower ambients.
Can this be an indication that I'm also losing gear and bearing protection ?
The lube in question is Redline MTL (10.2cSt @ 100*C, VI 171) in a pressure lubricated Land Rover R380 gear box.
The factory fill is Texaco MTF 94 (10.5cSt @ 100*C, VI 190). Prior to using MTL, I used Castrol Syntrans (PAO/ester, 11.9 cSt @ 100*C, VI 183) This is a Euro Castrol, designed for extended drain, heavy vehicle transmissions in Europe (MAN, Volvo and MB. They use synchro boxes exclusively)
I had the same 'problem' with the Syntrans.
All these gear oils appear to be biased towards cold temperature performance, which I don't need. The lowest it has ever been in winter here is -7*C, and the shifting is flawless, but we are in the middle of summer now, and even though I don't live in a hot area, it has been over 40*C about 5 days already.
I'm going to mix some MT90/MTL 50/50, but am reluctant to go any heavier as the gear box does have an internal pump that supplies all the bearings through internal drillings.
I'm currently logging 'box/oil temperatures on a transfer pipe, with the highest reading so far being 65*C on a 32* day after 30km. I have to do a 320km trip tomorrow, (to get some more Redline
Any thoughts, Ladies and Gentlemen ?
Or am I worrying over nothing ?
Rick.
