Thread: bad whiny transmission noise - listen here

I did know about viscosity but I did a bit of reading to update my knowledge since this discussion is getting more technical. I found some very interesting info.

"Thinner motor oils such as 5W-20 or even 0W-20 are becoming more popular these days and are even specified by some OEM's (FORD & HONDA) on new 2001 cars.

Although these oils are promoted as "energy conserving" they generally trade a gain of less than 0.1 MPG in Corporate Average Fuel Economy (CAFE) for shorter useful engine life.

FORD which has previously designed cars to have 10 year or 150,000 miles life has reduced the mileage life expectation to "beyond 100,000 miles" on vehicles that are operated on SAE 5W-20 Motor Oil.

HONDA only claims "useful life" as 7-years or 70,000 miles in EPA certifications for their CIVIC which uses SAE 5W-20 Motor Oil, while the previous model that utilized SAE 5W-30 Motor Oil was certified for 10 year or 100,000 mile durability.

Since both HONDA and FORD Warranty their NEW cars for ONLY 3-years or 36,000-miles the reduction in engine life expectancy is not a factor.

By contrast Mercedes-Benz recommends use of ONLY Synthetic Motor Oil that is at least SAE 5W-40! This is a recent increase in recommended viscosity from SAE 5W-30. Apparently customer research indicated that engine longevity is more important to typical MB customer than fuel economy."

Also did the all-round fluid change on my P38 when I got it about 2 yrs ago (105k km late 1999 BoschEFI). Lots of very fine grey stuff hanging off the magnetic diff plugs so I spent a good deal of time getting info from various manufacturers plus LR forums. I ultimately used the Castrol recommended diff oil plus the Nulon additive...

However for the transfer case I used Mobil Agri Fluid 424...80W as a result of searching the RR.net forum. It takes more than 2L ! Need to fill when cold until it begins to dribble from the filler hole.

It's especially formulated for wet clutch tractors etc and excellent for 4wd transfer cases ...but NOT auto transmissions. The quietness was amazing, it no longer sounded like the schoolbus I remember from the late 50's! A subsequent 500km trip confirmed the improvement.

just more info to muddy the waters!

cheers

thanks for the info. I think I do need to put a bit more in the transfer case. But I have been amazed since the day I did this work how smooth the car is running. It has fixed a lot of problems I just thought were normal, having not driven a RRC before. (except a thrashed out early 3 speed auto with shagged engine)

The syncros are now operating as they should and there is less cabin noise all round. I too found magnetic plugs with lots of swarf attached.

Originally Posted by Blknight.aus

given that that caveat IS in my original statement....


IVe seen an 8HA wiped out because someone put OEP600 (the military equivelent to 85/140) in it and went for a prolonged fast run The cause of death was overheating of the diffs front pinion bearing. Given that F4phantom is driving what (from the layout of the radio, ciggy lighter and heater controls) appears to be a midrange D1 he's more likely to be doing lighter fast work than heavily laden low to medium speed towing then the 80/90 is the way to go. Ever since the series there has been the scope for using 85/140 in hot conditions in diffs even the tcase. But the scope that your likely to encounter that in in Australia is pretty low

saying you've killed 2 rover diffs that were running 80/90 in them is like saying that it was the fact that smokers who get cancer have also drunk water so we shouldn't drink water as its potentially a cancer causing agent. I'd bet that theres a lot more diffs out there running 80/90 that haven't failed than there is than diffs running 85/140 that haven't failed..

I agree with the complete statement above. I have used nothing BUT 80w90 in all the diffs in all the vehicles I service and own. Some get a serious hiding. None have failed due to any kind of lubricant issue. I would run 85w140 in high ambient temps while heavily loaded,(+40degC)but only if it was convenient to change it out.

One thing Dave HAS seen a lot of, that is Series2/3's, perenties and 110's that cop a hiding from ADF etc drivers. So I guess he might just know a bit about what he is talking about here.
And I'm not sure where the reference to an accident or a death comes from? The '8HA death' Dave speaks of in the above is a Salisbury differential failure....
JC

Originally Posted by Blknight.aus

Given that F4phantom is driving what (from the layout of the radio, ciggy lighter and heater controls) appears to be a midrange D1 ..

Originally Posted by justinc

I agree with the complete statement above.
....
JC

I REALLY hope you don;t agree with the "whole" statement JC

Originally Posted by rovercare

I REALLY hope you don;t agree with the "whole" statement JC

Yeah I know THAT part isn't right, but that part isn't an IMPORTANT part!
Nit-picker!
JC

For those with ARB lockers, you should note what oil ARB recommend for harder off-road and for heavy/high temp work in the owners manual. 80/90 is only recommended for light/normal use of the vehicle or operating in extremely cold climates, otherwise they recommend 85/140. This is exactly the same as the point as I have been trying to make. If you drive your vehicle around town and only go off-road occasionally on easy to medium trips, then 80/90 will be fine. If you run bigger tyres, go on the harder off-road trips, or regularly tow heavier loads, you may want to look at something that does not thin as much when hot.

A rover diff is smaller than most 4wd's. Holding less oil means that it will heat up quicker and therefore how the oil reacts to heat becomes important.

Originally Posted by r.over

It is a little strange to me that people think that 80/90 is OK but 85/140 isn't. The cold viscosity is basically the same between the two oils. The only difference is that one does not thin as quickly as the other as it gets hot. Both oils get a lot thinner as they heat up.

If we were talking 80/90 compared to say a 130/140, I could maybe understand the issue. But we are talking about two oils that have virtually the same viscosity when at cooler running temps.

I like to be educated, so can someone explain it to me.

Our resident oils guru Rick130 will be able to explain the tech details off the top of his head, but as far as I can say, when running a differential under high load conditions and high temps the pressure exerted between mating surfaces is extremely high (Crownwheel to pinion etc) and this is where a 140 would help with GEAR FACE protection.
Under reasonable temps and pressures, IE 20+degrees and a Disco or RRC with less than a ton on the towhitch at highway speeds, the exerted pressures are very much less. Even moreso, with the size and therefore surface area specifically of a larger crownwheel and pinion like a 8HA salisbury differential gearset spreads the load over a LOT more tooth contact, there is little need to run heavier oil than 80w90 in these differentials IMHO.
The 8ha Sals bearing failure Dave was refering to was possibly due to running this 85w140 oil at high speeds where there is a possibility of an insufficient volume of lubricant (As it is splash lubrication) to the pinion bearings.

Hope I didn't make a mess of that explanation

JC