85w140 in rebuilt g/box HJ61

Submitted: Tuesday, Jul 26, 2005 at 12:18
ThreadID: 25061 Views:2616 Replies:4 FollowUps:2
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Hi there,

we just had the gearbox/transfer case on our HJ61 rebuilt in Kimberley. When we got home, I realized the mechanic filled them with 85w140 grade oil (presumably BP). We drove 5000km home to Wollongong, mainly in 5th gear. The gears now feel fine when they warm up, but when cold the 1st and 2nd are very, very stiff. I wonder if this wold be due to the high viscosity oil? Does this grade of oil give additional protection to the gears when they are still wearing in? In other words, should I change the oil to a lower grade, considering it is much colder here than in Kimberley, or should I keep it until the gears are worn in and just warm the oil up before driving off by running the engine in first gear with the transmission lever in neutral?

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Reply By: 120scruiser - Tuesday, Jul 26, 2005 at 12:27

Tuesday, Jul 26, 2005 at 12:27
Its a wonder you could change gears at all with that grade oil in it.
I would drain them and put 75w/90 in the gearbox and 80w/90 in the transfer case.
Selecting second gear would be a major drama with that grade oil.
AnswerID: 122101

Follow Up By: figtree - Tuesday, Jul 26, 2005 at 12:59

Tuesday, Jul 26, 2005 at 12:59
Thanks 120scruiser,

I wonder what was the reason for puting this oil in in the first place-this was done by a reputable mechanic-it may be that this oil prevents excessive heating up as the gears are worn in in the first hour of driving... When the oil warms up (10-15 min driving), it is actually easy to change all gears...

Should one do anything different with the reconditioned gearbox, to help wear-in without damage? would oils like Mobilfluid 424 be beneficial here (it is used primarily for heavy machinery-tractors etc, but is recommended for lc on this forum).

FollowupID: 377261

Follow Up By: 120scruiser - Tuesday, Jul 26, 2005 at 14:44

Tuesday, Jul 26, 2005 at 14:44
I am one of the advocators of 424 fluid.
I wouldn't use it in your 60 series. I use it in 80 and 100 series gearboxs as they run a different type of synchro set up to your 60.
Straight 75/90 will be fine.
Only recommendation is to change it regularly as 60's are heavy on input shaft bearings. I change my own every 12 months along with the rear LSD oil. With the change gets any metals out so it wont contaminate the rest of the box and diffs.
FollowupID: 377296

Reply By: Member - Davoe (Widgiemooltha) - Tuesday, Jul 26, 2005 at 12:28

Tuesday, Jul 26, 2005 at 12:28
my concern would be the thicker oil not splashing over the gears effectivly when cold
AnswerID: 122102

Reply By: Member - DOZER- Tuesday, Jul 26, 2005 at 13:35

Tuesday, Jul 26, 2005 at 13:35
Change your oil back to something that will work around here. (im in Farmborough heights) remembering it was in 30 degree temps that the 85/140 was used.... id leave whats in the transfer, and change just the gearbox oil. Suggest you get some Castrol vmx-m oil (75/80 or something like that) only because most of the people on www.lcool.org site use this after trying most of the rest.
The 85/140 means it acts as an 85 grade when cold and like a 140 grade when hot....or it stays thick like honey even when hot....this wont wear things out faster or anything like that, but will make things hard to change and possibly less likely to leak past seals etc (the 60's have a common problem with transfer oil being leaked into the gearbox) so for these reasons plus the temp up there, he has used this oil.

AnswerID: 122115

Reply By: figtree - Monday, Aug 15, 2005 at 16:01

Monday, Aug 15, 2005 at 16:01
Just to post a follow-up:
I couldn't find Castrol vmx-m, but my mechanic put in the VAlvoline DuraGear gbox oil and the problem is fixed.

Thank you all for the suggestions.

AnswerID: 125273

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