97 Nissan Pick Up, 5 speed manual, 192k. The specified oil is 75w90. When it was new, I drained to factory fill out and refilled it with Mobil one 75w90 synthetic and a bottle of Slick 50 for Manual Transmissions (I do not use Slick 50 in the motor). This has worked very well for me in past transmissions. Anyway, at around 160k, I would hear an occasional whine when at a steady 55 mph on level ground. If the road grade changed or I changed speed, it would go away.
At the 180k oil change, I decided to check the the transmission oil level. It was bone dry. The capacity is 2.1 qts and it took 2.1 qts to fill it. I filled it with Mobil One 75w90 again. I have checked it at each oil change and so far, it hasn’t lost any oil since I filled it. I still have the whine at 55 mph on level ground and it still goes away with any pitch or speed change.
Now my question, would there be any benefit to switching to a synthetic 75w140 or a conventional 85w140? I’m thinking that the 75w140 wouldn’t change anything but the 85w140 might. Opinions?
I expect there’s been some damage to the gears, and they aren’t meshing perfectly now. The first thing I’d try is to try the fluid Nissan specs, 75w90 conventional (non-synthetic).
damage is done, but the damage might not be fatal IF you keep fluid in the tranny. I’d stick with the specified weight. Whether it is Mobil 1 or conventional isn’t a factor at this point. Running it dry for likely a long time is the problem. Check the fluid level every 5 to 10K miles and top off as needed. Get used to the whine, and hope it stays the same without getting louder.
I think it is one of the bearings, but it might be gears worn too. Gears are “hardened” when they are made and once the hard outer layers of metal are worn off, the gear will deteriorate quickly. So if the noise stays the same either the gear(s) affected still have sufficient metal to last awhile, or it is a bearing making the noise.
PTFE is Teflon. And Teflon is a solid particulate which can damage bearings, shafts, and gears.
DuPont took SLICK 50 to court and argued that using PTFE as an additive in any oil is a misapplication of PTFE. And that it takes very high temperatures for PTFE to coat metals to create a slick surface. And adding an oil that contains PTFE can actually do damage because the PTFE never reaches the correct temperature. So it remains a solid particulate in the oil.
So, you might as well have added sand to the gear oil when you changed it out.
I tend to think your transmission is toast and it’s time to go shopping. Little or no oil will be the kiss of death in a short time anyway even on a transmission with additive-free gear oil.
Generally the mainshaft bearings are what starts going first with a lack of oil; whining and at some point the transmission eventually locking up.
The whine is essentially unchanged from when it first started. The transmission shifts perfectly and doesn’t make any other unusual noises. If it is toast, it’s not burned toast yet so I will keep it until it goes out completely. I only use the truck occasionally, I don’t need to depend on it.
I just wonder if going to a 75w140 or 85w140 would help or hurt the transmission. I see both on sale everywhere, but I don’t know of any vehicles that specify that gear oil, so who uses it?
At one time Subaru was having some synchronizer related gear crunch issues on their manual transmissions (even almost new cars) and oil heavier than 85/90W was used with no ill effects although I cannot remember off the top of my head what it was.
I remember some people were changing the gear oil and adding containers of STP engine oil treatment to stiffen the oil up even more in an effort to cure this problem.
(The root cause was poor synchronizer construction which would just flat not lock a spinning gear down during shifting.)
If it were mine I’d go with the heavy oil and it would really not hurt anything to overfill it by a small amount. As far as I know, the heavier oil and/or STP oil treatment use never harmed anything but on a 20 degree day cold shifting was a bit like rowing through molasses at first.
The only problem I have using a heavier oil is cold weather performance. I put 85w/90 in a transmission designed for 75w/90, and it became almost impossible to shift on a cold morning if the temps dropped below 30 deg. Fine once warm, tho. Changed back to 75w/90, and that went away.
Replace the seal on the output shaft and keep it full of oil,heck we used to pump a bunch of chassis lube in old leaky transmissions and never had one lockup-People please dont over maintain things,sometimes our good intentions ruin a perfectly good setup,I lost a seal in a rearend after switching to Royal purple and I know someone will say that didnt have anything to do with it
@keith I’ve had the same argument with myself over using 75W140 in a high mile differential that called for 75W90. With the synthetics, they don’t thin nearly as much in the very cold but the 140 weight should provide better hot protection, right? At room temp, they 75W140 is quite a bit thicker so maybe it won’t get into the smaller needle bearings as easily. I’d suspect the whine, being a higher pitch, may be one of the smaller needle bearings and you don’t want to risk starving it for even an instant at this point.
BTW, I argued with myself (thin oil! No! thick oil! No!) when I was writing this and changed back to thin before posting!
DuPont took SLICK 50 to court and argued that using PTFE as an additive in any oil is a misapplication of PTFE
Actually the lawsuit was for the name Teflon which Dupont owned. If you look at early advertisements the said the used Teflon. Now they say they use PTFE - which is the chemical name and can’t be patented. Dupont didn’t want Teflon associated with such a bogus product.
I don’t want to argue the merits or lack thereof of Slick 50. I used it, it seemed like a good idea at the time.
There does not seem to be a leak at this time. I should point out that this truck was my daily driver from when I bought it in 97 to when I bought my Saturn in 2002. When I got the Saturn, the truck was relegated to gardening and moving duties so it rarely got driven. For a period of about three years, I only put about 7k miles on it and I think the sitting around all that time was when the gear oil leaked out. It had about 150k on it when I quit driving as a daily driver.
It hasn’t lost a drop of oil since I refilled it. I’ve been checking at each oil change now, but I checked it about every 1k for awhile after I refilled it. Even though it does not seem to be deteriorating, I will check the level at every oil change from now on. I was just considering the idea of going with a heavier oil, but I am concerned that it might do more harm than good.
I appreciate the inputs so far. I haven’t decided yet.
Second question, since this truck gets into the mud from time to time, and I or my son will use it on snow and ice days (less to lose in case of a crash), and I am in need of new tires, is there a down side to getting winter snow and ice tires for year round use on the truck. I know they will wear out faster, but since the truck isn’t driven very much, that will not be an issue.
I have used snow tires year round but that was about 30 years ago when the technologies were different. Will winter ice and snow tires cause handling issues on dry pavement, highway speeds in the south in summer? No long distance driving, just local but some local on freeways.
I run winter tires year round on my 95 Nissan pickup. The set of tires I have on it now are five years old. So I’m going to need to replace them by next winter.
The reason I run winter tires is because they get great traction in mud.
I remember before they started calling them winter tires, they were called mud and snow tires.
Thanks Tester, good to know. I was concerned that with the new technology going into winter tires these days that they might have adverse characteristics for summer driving.
The next time I need tires for my Toyota Sequoia I am going to put winter tires on it. I put about 4K miles a year on it and much of that is in the winter to use the 4WD. The winter tires would be a big help with braking on some steep hills I have to deal with that are often slick and slippery in the winter. I will shop for Michelin X-Ice tires and I know they are made in a light truck winter tire of the correct size for my SUV. I have a set of General all seasons on there now, fine for going but not too hot when stopping or cornering on snow/ice covered roads.
@UncleTurbo If you are going to drive that little, good winter tires like Michelin X-ICE are OK. The little extra wear in the summer will make little difference in their overall life which should be about 10 years. Just make sure the air pressure is correct, especially for hot weather summer driving.