CHANGING TRANSAXLE GEAR OIL

My 1976 308 had a complete trans axle lube change exactly 3 years ago and about 1600 miles. Even though the car is on the lift, it's still a messy job. Any thought on whether or not I should change it out? I believe the factory recommends it at 15K miles. thanx steve

 

It’s not a messy job at all. No more difficult than an engine oil change. While it’s up there I’d just do it…

 

isn't it VERY SLOW if you fill it at the reservoir, instead of using a hand pump from below? thanx steve

 

I’ve done it twice on jack stands using this method and it’s not difficult at all. The hardest part is removing the wheel and fender liner: https://birdman308.com/service/Gear_oil/gear_oil_change.htm

 

thanx. I see in my original post that I erroneously called the transfer case the "reservoir" and was pretty non-specific about "filling it from below" when I should've said, filling the gearbox using the side filler plug. Oooops, steve

 

If the car has only done 1600 miles since the last gearbox oil change 3 years ago, why do you think it needs to be changed again?

 

Unlike the engine oil where you get combustion byproducts in the oil, the gearbox oil lives in an essentially sealed, benign environment. The oil breaks down through the shear of the gears with mileage. But for three years and low miles, there is no need for a change. Some gear oil probably sits on the shelf in its bottle for three years before it gets sold!

 

Thanks guys. Always looking for an excuse to get out of work! Since retirement, I've discovered that I'm even better at it than I was before! s

 

+308

 

Condensation.

 

Steve, we have seen those transaxles destroyed by rust brought about by condensation from service intervals like that.
As I recall Houston has some level of humidity.

 

I have never understood "condensation" re engines, fuel tanks, etc. In order for it to occur, the temperature of the material (in this case an engine/transmission/fuel tank), has to be colder than the surrounding air temperature. How can they get colder than the air around them under normal conditions? It's a mystery (to me)!

 

+1

Also condensation causes TAN (acidity) to increase

 

Condensation occurs when the air temperature drops below the dew point. The dew point is the temperature at which the relative humidity would be 100%. For a constant concentration of water vapor in air relative humidity increases as temperature drops. As the temperature drops below the dew point the air can not hold as much water vapor, thus condensation occurs.

 

Brian, Houston? Humidity? Say it isn't so!
Thanks, steve

 

BTW, Brian, As I recall, you like to fill the gearbox from the side, not from the top via the transfer case. Correct?. Thanks again, Steve.

 

'Condensation' in an engine can also just be from blow-by. Water is a byproduct of gasoline combustion, created almost pound for pound vs fuel burned.

 

The gear case is vented to the atmosphere, so I can understand your point. At the time these cars were manufactured, and Ferrari recommended gear oil change intervals of 15,000 miles (if correct), was that likely based on some reasonable amount of regular use, say 5,000 miles per year? Was time interval ever a consideration, i.e., 15,000 miles or 3 years, whichever comes first? I'm sure you will correct me if I'm mistaken, but it would seem that regular use of the vehicle for intervals of time that allow fluids to warm to operating temperature would mitigate the condensation issue.

 

Running a vehicle up to full operating temperature (stinking hot, as my one Grandfather used to say) on a regular basis mitigates many issues.

 

Are you referring to cars that have sat and never been driven for three years having their transaxles destroyed by rust?

What would a time based change recommendation for the transaxle be in a high humidity/temperature change environment situation?

 

I do. It takes forever to do it from the top and its messy. The top plug was provided to install a couple of ounces for the transfer gears. The rear plug was intended to be a fill plug.

 

If you look at the service intervals in their entirety it was assumed the cars would actually be driven at about 10-15000 per year. When the 308s were in production we had many being used as daily drivers.

 

Brian, Thanx so much. The car gets driven about once every 7-10 days, to full operating temp, and modestly hard. thanx, guys. s

 

This is what I’ve always assumed when looking at the QV Warranty & Service Booklet….it just seemed crazy to think that someone would put 15k miles/year on a 308…I don’t think I’ve ever put more than 10k in a year on any car that I’ve owned.
- Dave

 

The cost for MTL 6L is under $150 and these are metal contacting parts so is extra important.

I like to fill from the drop gear top in my Dino because it is over the top bearing feed and i feel good about fresh lubrications at this bearing.
Not sure about the 328 but to generally flush makes me feel good as i took the pan off and found the magnetc plug does not get all.