Need To Change Some Oil:

[Rob]

I've got several differentials, and transmissions that I plan to service in the near future. All are older with the newest being a 1978, Most are Mack. The exceptions are a single Fuller, (RTO12513), and a Brownie, (6231D), and a set of Rockwell rears.

Would 80W-90 meeting the GL-4 spec be good, or would GL-5 be better? Or a combination of both?

I know Glenn will know this from experience.

Thanks,

Rob

[theakerstwo]

use 85/90 allpurpose gear oil like rear end or 85/140 in the rear ends. Use 50w motor oil or mineral oil like white can aeroshell fore air plane engines in the RTO12513 and on the spicer trans with needle brgs use the same 50w. Do not use a multigear grease in the trans all tho some do but it can attack the synchro matieral and make it fail. glenn

[Bollweevil]

50 wt. mineral oil or engine oil for the 12513, but a word of caution, THEY WILL NOT MIX. Don't add one to the other, or you will h run the risk of having the result turn to sludge. Either is fine for your application. Although more expensive, for everyday or extended use the Eaton synthetic is a better choice. Your transmission could run 50 degrees cooler easy.

[Rob]

50 wt. mineral oil or engine oil for the 12513, but a word of caution, THEY WILL NOT MIX. Don't add one to the other, or you will h run the risk of having the result turn to sludge. Either is fine for your application. Although more expensive, for everyday or extended use the Eaton synthetic is a better choice. Your transmission could run 50 degrees cooler easy.

Thanks guys, my oil supplier can get fill any order I place but needs to know what I want......

I'll go with the synthetic if I know for sure the tranmission(s) don't leak! I actually have two RTO12513 transmissions, (I forgot about Project R-12) and have a fresh rebuilt one for that. The rebuilders tag specifically states to use synthetic gear lube.

Is it better to run synthetic in everything, or absolutely cost prohibitive in my cases?

Thanks,

Rob

[Bollweevil]

I haven't had an occasion to check prices in some time. The Eaton oil used to run about three to four times as much as engine oil. That's just another blast from the past. Engine oil is now four times what it used to be. I melted two 14715's in two years, before switching to Eaton synthetic. I could see the difference right away, prior to change over on a long gentle grade the engine would pull high gear. But the transmission temp would rise about as quick as the EGT, almost. I would have to drop a gear and back out of the throttle. After changing all I had to worry about was the EGT.

[Rob]

Today I went ahead and purchased a 5 gallon pail of GL-4 spec gear oil for some of my older transmissions that have brass syncros in them. I'm referring to the light trucks, and my passenger cars here. I've got a barrel of GL-5 multipurpose for the balance, and bought a 16 gallon drum of synthetic for the Eaton transmissions. Think I'll prolly have to sit down when the bill comes for that one!

Thanks again.

Rob

[theakerstwo]

Today I went ahead and purchased a 5 gallon pail of GL-4 spec gear oil for some of my older transmissions that have brass syncros in them. I'm referring to the light trucks, and my passenger cars here. I've got a barrel of GL-5 multipurpose for the balance, and bought a 16 gallon drum of synthetic for the Eaton transmissions. Think I'll prolly have to sit down when the bill comes for that one!

Thanks again.

Rob

The last that i used was about 105.00 to fill a eato 13 speed bying by the gallon but on mine it gets 50w motor oil.

[Rob]

The last that i used was about 105.00 to fill a eato 13 speed bying by the gallon but on mine it gets 50w motor oil.

I've got four Fuller transmissions now so it was a little less expensive to purchase the larger quantity. I don't remember the capacity of them off the top of my head but 22 pints each seems to ring a bell. That could be a Mack transmission though.

On another note, I've got an RTO-12513 and the slots were the shift handle engages are worn significantly. The slots that are used most often are worn almost concave where my fresh rebuilt ones are perfectly flat. Can a guy weld these up and machine them back flat, or should they just be replaced? We used to build up the forks in cars and light trucks with brass, then bring them to the proper thickness but this was for the fork part themselves.

Thanks,

Rob

[theakerstwo]

Rob if you are talking about the rails their self i think that they would worpe or bend in the progess of welding and then they would bind. Those trans maybe the 95 series had a binding problem any way. but the stick could be built up with brass and i have did that. I most cases you get more slack from the stick at the dognott inside t6he tower were the pins guide the stick inside the slots of the stick. I have built them up many times and grind out with a air cut off wheel and replace the two guide pins or bolts in the tower and then watch the driver get in and try it.When welding on the atick a man dont what to use no more heat than he needs because that is something that could break after over heating.

[marvgarr]

I've got several differentials, and transmissions that I plan to service in the near future. All are older with the newest being a 1978, Most are Mack. The exceptions are a single Fuller, (RTO12513), and a Brownie, (6231D), and a set of Rockwell rears.

Would 80W-90 meeting the GL-4 spec be good, or would GL-5 be better? Or a combination of both?

I know Glenn will know this from experience.

Thanks,

Rob

use only 80-90 in those eatons if you want them to last that synthetic crap is no good just alot of money for nothing it maybe great for bobtailing or a box truck or a little end dump but for any heavy hauling use gl5 gear oil we haul some good size loads out here about 160000 lbs we haul double belly dumps 2 full size 15 ton trailers and all we have in the trans is gl5 when i rebuild them i use gl5 in it never had a trany problem thats my 2 cents

[Rob]

Rob if you are talking about the rails their self i think that they would worpe or bend in the progess of welding and then they would bind. Those trans maybe the 95 series had a binding problem any way. but the stick could be built up with brass and i have did that. I most cases you get more slack from the stick at the dognott inside t6he tower were the pins guide the stick inside the slots of the stick. I have built them up many times and grind out with a air cut off wheel and replace the two guide pins or bolts in the tower and then watch the driver get in and try it.When welding on the atick a man dont what to use no more heat than he needs because that is something that could break after over heating.

Hi Glenn, I meant the top of the shifter forks where the stick end fits into. The area where all three shift forks are together at the top of the transmission that forms the gate for the shifter to slide through side to side. The stick is worn also and I can readily build that up, just don't know about the area that the stick contacts against to operate and slide the forks. They look like a forging to me so would readily take a weld.

Rob

[phantom309]

I'm not sure if synthetic oil is as important if you live in a warm state or mainly run your truck in the summer but up here in Canada almost everybody uses synthetic oil in heavy truck trannys and rear ends. I haven't had a truck with conventional oil for over twenty years but I can still remember starting trucks at 30 below zero and having to hold the clutch in because the oil in the transmission was so thick that it would stall the engine if you tried to let it out too soon. Then if you had an auxiliary trans you could put it in neutral and put the main in gear and let it spin to help it warm up. If you had a Roadranger and you pulled out of the yard too soon you sometimes couldn't get it to shift into high range until you'd driven a few blocks. Synthetic oil's great in a cold climate.

I notice that Eaton's recommended oil change intervals for a linehaul application are 120,000 miles for mineral oil or 500,000 miles for synthetic. I'm not sure if this still applies but at one time you HAD to use synthetic oil to be eligible for the extended warranties.

I really like synthetic oil but I sure wish it wasn't so darn expensive.

Jim

[Rob]

My only experience with synthetic oil is in my Ford compact tractor. With synthetic oil it really spins over fast when it is cold. In fact does not need to be plugged in during the cold to start. It does have glow plugs and starts easy with a proper warm up.

I don't mind the cost as I'll only do it once. Just have to ensure no leaks before the switchover. Don't want to add because of a leak.

Rob

[theakerstwo]

use only 80-90 in those eatons if you want them to last that synthetic crap is no good just alot of money for nothing it maybe great for bobtailing or a box truck or a little end dump but for any heavy hauling use gl5 gear oil we haul some good size loads out here about 160000 lbs we haul double belly dumps 2 full size 15 ton trailers and all we have in the trans is gl5 when i rebuild them i use gl5 in it never had a trany problem thats my 2 cents

Yes i am with you now and i have never done that to them but if you can do it i dont think it would hurt any thing as long as it dont srink the id of them and you cant get them back on the rails.

[theakerstwo]

use only 80-90 in those eatons if you want them to last that synthetic crap is no good just alot of money for nothing it maybe great for bobtailing or a box truck or a little end dump but for any heavy hauling use gl5 gear oil we haul some good size loads out here about 160000 lbs we haul double belly dumps 2 full size 15 ton trailers and all we have in the trans is gl5 when i rebuild them i use gl5 in it never had a trany problem thats my 2 cents

50 w will run cooler that 85w90 and on top of that some 85/90 muti gear oil will eat the snychronizer material and you have a snychro that has gone bad early. I know some guys use it cause i have been around them since the Rt series came out but had seen brgs go bad due to they dont lub as well with a heavy grease and they will run hotter because they are not lubing as well as with a lighter lub. I did waranty work for eaton for many years and now and for 15 years they would not cover waranty if the wrong lub was in it. When a snychro has the material striped off of it it is from the lub eating at it. It is not from wear because the matieral will come off around on the side that is not in contact with the clutch. Any one that does alot of tyrans work will tell you that heavy lub is were you find trans problems. The mack trans for many years did get a Gl5 hi pressure grease same as rear end but never has fuller before eaton got them ever remended a muti or allpupose gears. They did call for a mineral grease for years or a engine oil call aershell which was airplane engine oil of 50 weight. I have seen guys running the mineral grease and have heat problems going to ca. and then we change the grease to 50 weight univerial motor oil and it would bring the heat down. So for years i use 50 w motor oil Which i can get here at our oil jobber and they call it univerial or base motor oil. It is oil they by to use in making a motor oil for a certain customer. It is alot cheaper. I changed my trans about 3 years ago and i think it was about 35 dollars for 5 gallon but i know it is more that that now.