Thank you!
If you dig past the advertising garbage on gear oils you'll see most companies refer to GL4 as transmission oil and GL5 as differential oil. GL5 has additives to further reduce friction on gears and it also reduces syncro action because it is friction that allows them to work. In most Ferraris it is a combination transmission and differential. There is no perfect oil. In non hypoids a GL4 can be used. I really do not recommend it in transaxles with hypoids.
I agree a few ounces over is unlikely to affect anything, but if you have a fluid leaking out the front of the engine where the shift rod exits it will be engine oil, not trans oil.
Indeed, once the front seal is leaking, the internal one that seals the oil and gearbox sumps is likely leaking too. This will cause the two oils to mix, so it is probably time for the shift shaft seals replacement.
Hello Mr. Glassman, Thank you, I found my handbook and found the Oil Level Plug. Opened it to change the Copper Crush Washer and check the Oil Level. My car is on Jack Stands and the Nose is down. As it sits, the Gearbox Oil is just coming out the hole. I realize the car needs to be on the level. I am wondering how much extra oil can be in there before it becomes harmful. Thank you.
We are going to be addressing the Oil leaks and the Clutch replacement at the same time, sometime in May 2023. I believe it can go on for now as it is. Just wanted to know if Gearbox Oil Levels will adversely affect anything. Thanks.
It can overwhelm the breathing system and cause leakage. The way you did it is quite common and I avoid it. It can end up far higher that you expect.
I think some of the confusion could be attributed to comments - a) getting 6 quarts of oil b) using 4 quarts and then adding "some more", (for good measure, etc.). Also a comment about running the gearbox oil level higher because the 5th gear was located higher in the box...!!! Some of us take things to literally! After looking at things from under the car, I came to the conclusion that if Ferrari put in a Oil Level Drain Plug at the rear of the gearbox, they must want you to use it! Fine!! So that is what I have done. When the car is on the level, an additional 4 to 5 oz. is not going to make that much difference to the Oil Level spread over the entire gearbox. Maybe 1.0 mm to 3.0 mm. For those of us concerned with the "correct level", I'd say judge it by the Oil Level Plug at the rear of the gearbox. When the vehicle is running and all the gears are turning, the oil level is constantly changing anyway, correct? As someone mentioned earlier in this thread, maybe we are "sweating" this too much!
When running it looks like a blender inside and oil goes everywhere internally. The level is not the issue. It is only a means to statically measure the volume of oil. Running does not change the volume and the volume is what is important. When overfilled we see far more leak issues. Want leaks? Its OK with me. .
Having said that, I believe the larger question is whether we should use a 75w 90w grade "dino" oil or a modern day Synthetic oil. There is also the question of a GL4 or GL5 oil. One is good for gearboxes and the synchro's, which brings up whether they are brass / bronze (Yellow) or steel as I hear the GL5 tends to attack the yellow metal synchro's. GL4 is supposed to be good for gearboxes and helical gears, and a GL5 for differentials with hypoid gears. Am I right in asking what do we do in a Ferrari with the gearbox and the final drive running in the same oil? And finally, should we use a friction modifier with a GL5 Synthetic oil? For your information, I am currently using a Redline 75W 90W Synthetic with Friction Modifiers for the Limited Slip Differential. Then again, I have 2 x 4.0 oz. containers as 1 x 4.0 oz. is good for 2 quarts and 2 x 4.0 oz. containers for the 4.0 quarts of oil in my car. I know a lot of people with a lot more experience have been through this before, and I apologize if this is opening up the same can of worms! Hopefully someone out there is going to write up a short, definitive comment. Thank you in advance!!
A wiseman comment said: Leaking is good, means there’s oil inside When leaking stop is what I’m worried about.
No, good questions. Your car has sintered iron syncros. I am not big on experimentation with others cars. I had client with a QV that was a daily driver. I inherited taking care of the car from another guy I knew who retired. The car had over 100,000 miles on it. It shifted like butter. When time came to change the oil it had red gear oil. I put regular GL5 in it. It suddenly quit shifting so well, OK but not like before. I contacted the old mechanic and asked. He told me it had been using MTL for most of its life. That experience set me off on long research on gear oils and I have been using MTL or MT90 in non hypoid Ferrari transmissions ever since. As for LSD addtives GL 5 may or may not have it. The product should say. I find most Ferraris LSD make little or no noise without it. Some make a lot. My 328 doesnt make any noise with MTL , my TR makes a little noise with 75-90NS, I choose to ignore it. If there is no noise there is no reason to use it. It like GL5 intentionally have properties that inhibit syncro operation. As for synthetic vs Dino oil. Again I am not big on experimentation. I stuck with Dino oil for a very long time. I was also a crew member on a Land Speed Record car for years. Our engine guy was a dyed in the wool Dino oil guy. Our cars had telemetry on them and we recorded everything every pass and kept in the log. One trip to Bonneville Redline talked our engine guy into switching to synthetic and gave us a whole bunch of stuff. After a couple of passes we started going over the telemetry data and saw a lot of before and after changes. At the end of the year the Rodeck Chevy engine was torn down and the combination of of all that made me a synthetic believer. I never use it in pre 4 valve Ferraris because the old piston ring combination burn it like crazy. In the transmissions I think synthetic is superior in all of them.
I went to MTL in my 328 years ago based on RifleD recommendations here and it was dramatically better than the Motul that was in there at the time. I accidentally (!) drained it last year and refilled it with Lucas gear oil because I had it on hand. Car went back to being a recalcitrant shifter. Ordered the MTL, changed back and once again, smooth shifting. Use MTL!! Re Dino/synthetic oils - had a similar experience in drag racing many years ago. On a 1968 426 Hemi Barracuda SS car we used Valvoline 40 wt. Oil guy in the pits talked up Mobil 1 so much that to shut him up we tried 40 wt Mobil 1. Got 25 FREE HP on the dyno and relevant track times. That may not sound like a huge number on what was, at the time, an 800HP car (now those '68 SS Mopars are making 1100+), but if you have 25 more HP than the guy next to you, assuming equal driving, you win the race.
The GL4 Redline MTL is great choice for these gearboxes, and gives the best shift quality. I have tried other brands and Redline products, and MTL simply gives the noticebly best shift action, cold and warm, my gearbox shifts like butter. Also having the shifter shaft aligned correctly makes a big difference, probably more a cause of shift issues than the gear oil fill. I always fill to the gear plug level, you jack the car, put jack stands, take out the level plug, remove jack stands and lower the car so it is level. Fill til oil runs out, and let it run out for a while. The jack up, put jack stands in place, crawl back under and put the level plug back in. Be really careful threading that plug, it is too short a thread, and can cross or damage the casing threads. Ideally get the longer thread reach plug from Hill Engineering. A little bit of overfill (probably 1/3 a quart) apparently is done by some racers, but I prefer to simply fill to the correct level as noted.
There are some GL5 oils available that are safe for yellow metals, synchros etc. Amsoil Severe Gear 75W-90 is one of them. I use this in my GT4 and works like a charm. Many others are using this oil in their 308's with good results from a quick search on 308 gear oil. Redline also good if you use the correct oil for our application.
I tried this, and shift quality was not good, second gear problem, notchy. I was surprised how much difference a type of gear oil can make, and like with you, others had recommended it so I tried it (in my 1988 Mondial 3.2). It does appear that for whatever reasons, different gearboxes seem to respond differently to different oils.
The plug thread is not too short. It can survive being massively overtorqued. What hurts the threads is being cross threaded.
I saw this conversation. I seldom go on this site anymore. I was probably one of the 1st who posted concerning Redline. I had called and spoke to one of the guys there. They suggested trying the non-slip stuff 1st. I did and that is all I have used for now over 20years plus. Low fill, over fill where it runs out the back hole, no problem, not rocket science on these great cars.....
Yep, I switched to Redline MTL several changes ago and was actually amazed at how much better the car shifted from 75/90NS. I read something here about it. Again, another fchat knowledge sharing of experiences.
There is quite a few but yellow metal compatibility isn't the issue. The Ferrari made transmissions had iron syncros up until and including 348, 512TR, Mondial t.
