AeroNautical Posted December 29, 2013 Share Posted December 29, 2013 As per recommendation on the forums, I'm running 10W-30 full synthetic in my ax-15 to protect the syncros. Having almost 200,000 miles on the tranny, it makes some noises when it's warm. It shifts buttery smooth (except into reverse, unless I double clutch it) at all temps, but I'd like to hush it up with some gear oil additive. Would it be alright to add that to the 10w-30? If so, any brands and types you'd recommend? Link to comment Share on other sites More sharing options...
Jeep Driver Posted December 29, 2013 Share Posted December 29, 2013 Lucas oil stabilizer....50/50 with oil. Link to comment Share on other sites More sharing options...
92tanMJ Posted December 29, 2013 Share Posted December 29, 2013 I personally would ditch the 10w30 first and switch to Redline. I run the redline MT 90, which is 75w90. Ive heard nothing but good things about it. Little info on redline vs 10w30 http://www.redlineoil.com/content/files/tech/MTL%20and%20MT-90%20Tech%20Info.pdf http://www.amazon.com/Red-Line-50304-Transmission-Transaxle/dp/B000CPCBEQ Link to comment Share on other sites More sharing options...
skidoo_j Posted December 29, 2013 Share Posted December 29, 2013 I too am running the Redline MT 90. I would recommend it over the 10/30 as well. Mine is quiet and shifts very smooth. Link to comment Share on other sites More sharing options...
1987Comanche Posted December 30, 2013 Share Posted December 30, 2013 I use synthetic 10W-30 with 1/2 bottle of Lucas. Link to comment Share on other sites More sharing options...
JeepcoMJ Posted December 30, 2013 Share Posted December 30, 2013 Engine oil is a terrible idea. Run the redline. It has the necessary additives and detergents, and does not have the ones that Are harmful to the brass synchros. The weight of that oil doesn't come close to being accurate for what you need in gear lube. Link to comment Share on other sites More sharing options...
Rockfrog Posted December 30, 2013 Share Posted December 30, 2013 motor oil and gear oil is rated much differently from each other ... most manual transmissions prior to the mid 80's shipped with either 10w30 or straight SAE 30 weight oil. Gear oil is closest in consistency to SAE30. Link to comment Share on other sites More sharing options...
1987Comanche Posted December 30, 2013 Share Posted December 30, 2013 Ma Mopar recommends 30 weight motor oil in the AX-15. The local dealer service or parts counter should be able to confirm for you. Link to comment Share on other sites More sharing options...
JeepcoMJ Posted December 30, 2013 Share Posted December 30, 2013 Yes, and most engineers are completely inept. Mopar recommends 50 ft lbs on an stud for the oil cooler on an 06 kj diesel. That doesn't make them right. They use that because it was the cheapest way to get away from the damaging additives in regular gear lube. Read that again. THE CHEAPEST WAY. Cheap in no way, shape, or form, is the proper or even mediocre solution. Link to comment Share on other sites More sharing options...
Jeep Driver Posted December 30, 2013 Share Posted December 30, 2013 I can no longer tolerate the odor of gear oil. I will not pay $68 a quart for Redline. I have another trans that will go in in the next week or two, it will get 1qt of Havoline 40 and 1qt of Lucas.......and it will be damn happy with it too. :P Nascar uses motor oil in engines that twist 9800rpm for 4-5 hours but we don't trust it in a gear box to tool round town........lol........ Link to comment Share on other sites More sharing options...
JeepcoMJ Posted December 30, 2013 Share Posted December 30, 2013 Something is wrong if you have to smell gear oil often. I don't like the smell of most fluids, but it is something that must be tolerated. You can all obviously do what you wish. I go with tried and true, and by god I will never trust an automotive engineer. They are the reason I am in business. Link to comment Share on other sites More sharing options...
gogmorgo Posted December 30, 2013 Share Posted December 30, 2013 So you design your own cars? Thought you drove Jeeps. Gear oil is rated differently so you don't mix the two; not because motor oil won't hold up to use in gears, but because gear oil won't hold up to the temperature and contamination from the motor. Link to comment Share on other sites More sharing options...
92tanMJ Posted December 30, 2013 Share Posted December 30, 2013 I can no longer tolerate the odor of gear oil. I will not pay $68 a quart for Redline. I have another trans that will go in in the next week or two, it will get 1qt of Havoline 40 and 1qt of Lucas.......and it will be damn happy with it too. [ :P] Nascar uses motor oil in engines that twist 9800rpm for 4-5 hours but we don't trust it in a gear box to tool round town........lol........ $68 a quart? :hmm: It's like 15 a quart off amazon with free shipping.. Ma Mopar recommends 30 weight motor oil in the AX-15. The local dealer service or parts counter should be able to confirm for you. That is actually a miss print, if youre talking about where its printed in the manual. Link to comment Share on other sites More sharing options...
JeepcoMJ Posted December 30, 2013 Share Posted December 30, 2013 So you design your own cars? Thought you drove Jeeps. Gear oil is rated differently so you don't mix the two; not because motor oil won't hold up to use in gears, but because gear oil won't hold up to the temperature and contamination from the motor. No, I do not. I am saying that tried and true fluid is what belongs in there. I don't care that motor oil will hold up to use in the gears. I care that the job is done right, and putting motor oil in the transfercase is akin to putting ATF in an engine. Sure, it may quiet it down, but is it doing it's job, or covering up something incorrect? It's too thin anyways. Link to comment Share on other sites More sharing options...
Oyaji Posted December 30, 2013 Share Posted December 30, 2013 Worth reading, the accompanying article can be found here. Link to comment Share on other sites More sharing options...
mvusse Posted December 30, 2013 Share Posted December 30, 2013 So you design your own cars? Thought you drove Jeeps. Gear oil is rated differently so you don't mix the two; not because motor oil won't hold up to use in gears, but because gear oil won't hold up to the temperature and contamination from the motor. No, I do not. I am saying that tried and true fluid is what belongs in there. I don't care that motor oil will hold up to use in the gears. I care that the job is done right, and putting motor oil in the transfercase is akin to putting ATF in an engine. Sure, it may quiet it down, but is it doing it's job, or covering up something incorrect? It's too thin anyways. We are talking using 10W30 motor oil in a manual transmission, as recommended by the manufacturer. Do not believe anybody mentioned running motor oil in a transfer case. Link to comment Share on other sites More sharing options...
JeepcoMJ Posted December 31, 2013 Share Posted December 31, 2013 Meant trans. Auto correct. Link to comment Share on other sites More sharing options...
Comanche_Fanatic Posted December 31, 2013 Share Posted December 31, 2013 don't screw up the transmission dude. Motor oil is for motors, gear oil is for transmissions/axles. Get 2 bottles of 75w-90 from autozone with pump for $23 and call it a day. You absolutely cannot say 10W-30 and 75W-90 are close. Way different weights and additives. Link to comment Share on other sites More sharing options...
Jeep Driver Posted December 31, 2013 Share Posted December 31, 2013 Been running Lucas and motor oil in the front axle and final drives on my tractor for a year now........it's all good. I'll let you know how it works out in my AX5. No fear. Link to comment Share on other sites More sharing options...
nitroxsteve Posted December 31, 2013 Share Posted December 31, 2013 I am running 10w40 in both my transmission and transfer case for a couple years now with no problems. Shifts better than when I was running 75/90. Link to comment Share on other sites More sharing options...
AeroNautical Posted December 31, 2013 Author Share Posted December 31, 2013 Guess it's safe to say noone agrees with what should be put in the transmission. I know gear oil is BAD for an AX-15 because of the brass syncros, which is the whole reason I used synthetic 10w-30 motor oil, recommended on this forum. I don't like the idea of spending over $60 to fill it with redline, however the reviews are damn good, and it's one of those "how often do you change the oil in your transmission?" situations, it might just be best to drop the money on it and forget about it, especially if it shuts the tranny up. Link to comment Share on other sites More sharing options...
Oyaji Posted December 31, 2013 Share Posted December 31, 2013 don't screw up the transmission dude. Motor oil is for motors, gear oil is for transmissions/axles. Get 2 bottles of 75w-90 from autozone with pump for $23 and call it a day. You absolutely cannot say 10W-30 and 75W-90 are close. Way different weights and additives. No, actually the viscosities are quite similar (go have a look at the chart I posted above). The method of checking viscosity is different for motor oil and gear oil, thus the apparent difference when comparing the numbering of the two. The main difference is the additives, as you mentioned. Here is an excerpt from the Redline PDF that Zack linked earlier that mentions why this is important: All oils are slippery, and with most lubricated components, the slipperier the better, but this is not so with manual transmissions. The synchronization of shifting gears requires friction to transfer energy from the synchronizer, which is locked to the input shaft, to its mating surface attached to the gear to be locked in as the drive gear. Few modern transmissions use sliding gears to change gearing other than for reverse gearing. Synchromesh transmissions have the gear pairs constantly in mesh. The drive gear is selected by using the shift forks to slide a synchronizer ring, which rotates at the same speed as the input shaft, in contact with the selected drive gear. Once the drive gear is brought to the same speed as the input shaft, the locking ring on the synchro assembly is allowed to slide over and lock into the drive gear. The time this process takes depends on how easily the synchro ring moves and the rate of frictional energy transfer between the two synchronizer surfaces. Higher viscosity lubricants slow the sliding of the synchro ring on the input shaft and require a longer time for the oil to be squeezed out from between the mating synchronizer surfaces. After the lubricant is squeezed out, the coefficient of friction of the lubricant determines the rate of frictional energy transfer between the two surfaces. Slippery lubricants such as hypoid gear oils can take too long to synchronize the gears, which promotes synchronizer wear. Red Line MTL and MT-90 has a coefficient of friction which is greater than conventional oils, allowing a quicker transfer of frictional energy. The graph below shows the desirable friction curve demonstrated by Red Line MTL compared to conventional lubricants. Note how the coefficient of friction is greater for the MTL than all others except the motor oil. Some motor oils have an adequate dynamic coefficient of friction, but most have problems with the static and low velocity coefficient of friction which can result in clashing. Clashing of the gears (actually clashing of the synchromesh gears, since the drive gears are always in contact) can occur if excessive shift effort is used in order to shift the locking ring into place before the surfaces have achieved equal speed. It may also occur at the end of a reasonably smooth shift if an instability exists in the coefficient of friction, causing stick-slip to occur. In this form of clashing, the ring slides on the mating synchro gear, but a sudden slippage causes a grinding of the gears. In order to prevent stick-slip from occuring and the gear clashing which results, the coefficient of friction should inflect downward as the relative speed drops to zero. http://www.redlineoil.com/content/files/tech/MTL%20and%20MT-90%20Tech%20Info.pdf The bit highlighted in red above I found the most interesting difference in the results offered by motor and gear oil. Note the mention that "some motor oils have an adequate dynamic coefficient of friction, but most have problems with the static and low velocity coefficient of friction which can result in clashing." Too bad they don't mention just which motor oils are perfectly acceptable - because their [Redline's] implication is that *some* are! I guess one solution would be to try a given motor oil in a gearbox and see the results for yourself; if you experience either clashing of the synchromesh gears when making fast shifts or stick-slip clashing when shifting normally, change to another brand, but if OK, then run with what you have in it. If you do go this route, please post your results. :) (Incidentally, I saw an earlier mention in this thread that motor oil was specified in the owners manual for some model years - was any particular brand of motor oil specified? I know that there are some very basic differences in how motor oils are formulated, which vary by manufacturer. One that comes to mind is the Castrol brand, which iirc is "parafin based", whereas other brands are "mineral oil based". It could be that the base makes a fundamental difference in the curves of their respective coefficients of friction. I'm sure there must be at least one SAE paper written on the subject, if anyone is interested in pursuing this further... but right now I am about tired of researching the subject!) There is a nice graph comparing coefficients of friction for motor and gear oils in the PDF that is worth a look, but I couldn't get it to paste here so if you want to see it you'll have to follow the above link. Here is some more info from the site I linked earlier worth a look - the entire page is worth reading too, for that matter: Automotive Gear oil chemistry differs considerably from motor oil chemistry in the types of anti-wear additives that are used in the formulations. Motor oils rely upon a Zinc-Calcium anti-wear structure, and Gear oils generally rely upon a Sulfur-Phosphorus anti-wear structure. (Considerable other differences exist in each of the types of fluids as well). Temperature and pressure activate the chemical EP (Extreme Pressure) components in gear oils. This chemical reaction provides slippage & protection to the gear face. Gear lubricants have a very distinctive odor associated with them, and this is generally due to their additive structure. Many gear oils maintain chemistry to reduce chemical attack of soft metals, and when the consumer selects a product, they should always be aware of what type & specification of lubricant the equipment manufacturer recommends for the application. One important thing to point out with gear lubricants is that they are not classified on the same viscosity scale as crankcase motor oils, and their viscosity relationship (not Load Carrying Ability or application read-across) may be approximately summarized as follows, 75w90 gear oil = 10w40 motor oil, 85w gear oil = SAE 30 motor oil, 90w gear oil = SAE 40 motor oil. The chart gives an accurate visual relationship of viscosities of different oils that are typically used for gear lubrication. http://www.torcousa.com/innov-lub-101.html Link to comment Share on other sites More sharing options...
mvusse Posted December 31, 2013 Share Posted December 31, 2013 don't screw up the transmission dude. Motor oil is for motors, gear oil is for transmissions/axles. Get 2 bottles of 75w-90 from autozone with pump for $23 and call it a day. You absolutely cannot say 10W-30 and 75W-90 are close. Way different weights and additives. Problem is GL5 contains sulphur that will eat the brass synchros. The original specification calls for GL3 which is not available anymore. GL5 gear oil is for axles, not transmissions. Link to comment Share on other sites More sharing options...
JeepcoMJ Posted December 31, 2013 Share Posted December 31, 2013 Agreed. This is a touchy subject any way you go about it Link to comment Share on other sites More sharing options...
Comanche_Fanatic Posted December 31, 2013 Share Posted December 31, 2013 I agree on using gl3 vs gl5, one thing that has me puzzled is alldata says use gl5 on ax15s, oddly. My 2 cents would be with redline 75w90, would only need like 3 litres. Somebody needs to correct this on alldata for sure tho Link to comment Share on other sites More sharing options...
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