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Differential Oil Grade
I am in the process of replacing a rear hub oil seal and brake linings, i will take this opportunity to switch over to a synthetic oil in the differential.
I am making the switch to try to reduce operating temp, i currently run conventional gear oil at 85/140 grade and often see diff temp of 230.
To those that are running synthetic in the rear axle, could you please advise the grade of oil that you are running.
Thank You
Gordon
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23 Replies
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same…either 80-140 or 85-140…can’t remember
BTW, 230 isn’t bad but I would change to synthetic. I’m using stemco wheel seals and have had better results than others.
1999 XLV X-6872, liberty #440 -
Thanks for the info, will switch to the synthetic and monitor the temp.
230 is my normal running temp but this year running from Spokane to kennewick there is a long stretch, maybe 3 hours straight on cruise at 65 MPH i can see the temp approaching 245
Today i removed both drive axle hubs, before removing the axle hub bearing nuts i checked the hub end float, there was zero play, this could cause an increase in temp as there should be between 1 to 10 thou end play, every little helps i guess
Thanks again
Gordon
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The hub for our coaches has very specific specs regarding tightening and that spec is called out in the service manual for the coach. There are two different specs, one calling for tightening to a certain torque value and then backing off a certain amount. But for another vintage coach service manual the spec describes end play so make sure the hubs are tightened to the specification for your coach.
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Amsoil is the best synthetic available but costly.
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I’m just curious as to how you would know any specific brand is better than the others.
I might be wrong, but I assume large oil companies have and continue to make serious product development efforts and that they invest huge sums of money for constant product improvement, yet a relatively small company is developing the best products?
If the product meets the certification standards it is doubtful any of us have the miles or years of experience to evaluate product performance.
What are fleet owners using and how did they arrive at the decision?
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This is what i use in my Bus.
https://www.amazon.com/Castrol-37517-Syngear-80W-140-Lubricant/dp/B00B9XDRC0
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I use non-synthetic 85-140 on my King Aire and that is what came stock on it. No reason to use synthetic and pay more. I don’t know or care what the temperature is. Make sure the oil level is correct and run it.
We never had axle temp gauges on a single truck we owned and never had a lubrication related failure in any of them so I don’t think it is as big a deal as some think it is. We did service every truck every week at some level, so they were looked at for leaks etc. and that is probably more important than anything.
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When in doubt … Prevost PASS!
https://prevostcar.com/contact/pass-247365-assistance
PASS offers 24/7 availability 365 days a year. Just call 1-800-463-7738
How many Prevost owners have a differential temperature gauge? We don’t on our 1999 Liberty XLV.
My background is not trucking, its common sense, flying many years ago, and racing NASCAR type race cars. Intuitively putting 450hp +/- through a single differential pulling 52,000# of coach and toad down the road puts more stress on our single differentials than say 375hp pulling 80,000# (or often less) through two differentials. (I base that on common sense.)
Running at 63/64mph on fairly level ground like Jon and I do probably doesn’t put an enormous strain on the diff. But pulling an 18,000# stacker trailer (66,000# plus total) through the mountains at 70 to 75mph should put a significant amount of strain on the single diff. Here I would certainly opt for a diff temp gauge. What are the diff temps? How much do they change with the trailer? How much do they change climbing hills and mountains?
If they stay (I’m just picking numbers) in the 230* to 250*, I’m not worried. But if they climb to over 300* … now its got my attention. Same goes for the transmission.
All lubricants breakdown and lose their effectiveness as the temps soar. Each has its own temp range. If you know it, then you can use a diff temp gauge to monitor where your diff is in the recommended temp range.
I’ve been to two racing lubrication seminars put on by Lake Speed Jr. when he worked for Joe Gibbs Racing Oil (which I use; now “Driven Racing Oil”), probably some of you have been there too. IIRC there are only two, maybe three providers of the base stock used in synthetic lubricants. Just those few. Everyone buys from them and adds additives. From what I recall from what Lake and his accompanying engineer said, its the additives which make the difference. That might answer Jon’s question about one lubricant vendor being favored over another. When I bought the race engine and car in 2005 my engine builder said to use Mobil 1 synthetic right off the shelf at Fleet Farm or Walmart. A few years later he called me and said, “Stop! EPA has had the zinc and moly pulled from street oils and its causing upper valve train problems. Use Joe Gibbs!”
Do our coaches need diff temp gauges? Most of us probably not. Would it be nice to have a diff temp gauge in the coach to monitor trends? Maybe see a problem developing before it becomes catastrophic? Of course. Especially if you pull a heavy load, at higher speeds, in hilly or mountainous areas.
How many coach owners have a diff temp gauge on their coach? What converters spec’d them? I presume they would be ordered with the shell from Prevost.
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My guess is that diff temp is not nearly as big an issue on trucks, Our coaches have limited cooling air flow and diff temps become critical at high speeds, high ambient temps, and if you’re towing a heavy load. I have a 300F oil temp gauge on my diff and I could peg it if I wanted to.
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My 92 CC does not have one.
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Joe you make very good points about lack of airflow on a coach versus a semi tractor. Under what conditions can you peg the diff temp gauge?
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Can’t be too important since none of my 3 Prevost’s had differential temp gauges. There is somewhat more airflow on a truck, but the truck runs more miles per day than most coaches do, and many more per year with a higher load all the time in our case. We were close to 80,000 about 85-90% of the time. All the engines were 435 or 450hp.
You can run what you want, but it is not what I will do, and not really necessary. If it was, everyone would be using it (synthetic), and everyone would have a temp gauge. Another good question, how many even look at the gauges they have or do a thorough pre-trip or post trip inspection? I bet not too many from some of the questions I have seen over the years.
My King Aire has 605 hp at 1950 lb-ft and I run pretty much 70+ every trip. I don’t pull a trailer and never will, but I do pull the Jeep Wrangler almost 100% of the time. My King Aire weighs a bit over 52000# so not much difference from my Prevost’s.
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Mark,
Why don’t you explain to Moses up there how 1 axle drives the tandem on a truck. It would take an hour to straighten out all his common senses.
Truk is hiding.
Later
bv
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It would take more time than I have right now…
. I guess tandem axle technology is something he has never researched or experienced. Or power dividers etc. Or 7, 8, 9, 10, 13, 5+3, 5+4, or 18 speed truck transmissions either.
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