Hi von Trapp,
yes Eaton-Fuller carried out much research into their constant mesh gearbox oil requirements in the late 1980s
Then, most Truck Fleet owners were using a SAE90 GL1 gear oil - Eaton offered the recommendation of that or an SAE50 engine oil above -12C (10F)
(Many fleet owners simply used a 90EP (GL5) gear oil which caused many problems)
Increased component longevity was confirmed when using a SAE50 synthetic oil all year round. This was especially so with seal and bearing life
They permitted OCIs being raised from 50k to 250k
They confirmed that changing to a synthetic could cause problems if done after initially using a mineral lubricant for 50k or more. They advised monitoring seals for 10k or so
I have used two synthetic SAE50 oils for nearly 15years in Eaton-Fuller Roadranger gearboxes;
Castrol's Syndrive 50E and,
Mobil's Mobiltrans SHC50
These oils have been used in 13spd, 15spd and 18spd gearboxes, the latter with double OD. We have never replaced a gearbox oil seal or opened a gearbox up in 10years!
According to UOAs, both have performed the same keeping new shift feel for over 1m kms. This has always amazed me considering that between 250000 and 300000 gearshifts are likely and I do not change the oil for 1m kms
Our gearbox lubricant change technique is;
1 - change out new vehicle's oil prior to 5kkms (3k m)
2 - monitor levels, seepage etc
3 - change filter (if fitted) every 200kkms (125k m)
4 - monitor oil via UOA at 400kkms (250k m)
5 - change if 4) indicates or at 1m kms if the vehicle has not been disposed of
Our gearbox's operating oil temperatures are;
Average: 86C
High: 100C
Low: 75C
We operate in ambient extremes of from -10C to 45C+
Eaton-Fuller also noted that consistent oil temperatures above 120C (250F) will shorten the oil's life. Intermittent temps to 150C (300F) are permitted
I hope this helps
Regards
Doug
[ July 06, 2005, 05:19 PM: Message edited by: Doug Hillary ]
