Is Mobil 1 75w-90w LS good or bad for 1997 Boxster 5 speed manual Transmission.

[boxstermuscle]

I put this oil in about 2k ago. I could swear the car is not shifting as smooth as before.Also the transaxle is louder .

Edited September 10, 2021 by boxstermuscle
mispell

[Ike84]

I think you've already answered your question. 

 

That oil is not approved for the g86 tranny.

[boxstermuscle]

Hi Ike,

        If you go to Mobil website you will find that they are non-committal when it comes to transmission oil. Yes,they  do have a function on website for engine oil and nothing else.I reach out to them a couple of days ago and I am waiting for a reply.As a man that totally brought a Boxster back to life after a rollover I am pretty good.I was responsible for all recalls,because Porsche wrote me off.Right now I am going to Redline which has a lot of information regarding my car.

[JFP in PA]

Porsche has typically used gear oils that are designed to their specifications, particularly in the five speeds because of the synchro ring materials of construction.  As the result, the factory fill gear oils lack any API or "G" gradings because they are unique.  A lot of the smaller aftermarket suppliers claim they have "equivalent" products, that in reality are not.  Over the years, I have lost count of how many gallons of aftermarket gear oils we have drained out of customer cars due to complaints of poor shifting, particularly in the cold, noise, etc.  And that includes a lot of Redline, Royal Purple, and Amsoil products. And except for transmissions that had sustained damage while using these aftermarket products, every time we switched the car back to the factory fill, all the customer's issues disappeared.

 

Years ago, we contacted all the major gear oil vendors looking for a true match to the factory gear oils; Mobil 1 summed up best when they told us that "Porsche uses totally unique gear oil formulation requirement's, which are made to their specifications, and which do not match any of our off the shelf offerings. And as Porsche represents such a small segment of the overall market, we will not be attempting to replicate their formulation requirements."

[Silver_TT]

be very careful, i had a gearbox that was destroyed because the previous owner used aftermarket transmission fluid.

 

also Porsche has changed their recommendation over time.  last I looked they are now recommending Shell transaxle gear oil , at least for the 996TT's Getrag.

 

this ain't like motor oils where it's "take your pick"..........

[boxstermuscle]

Hi Ike,

        If you go to Mobil website you will find that they are non-committal when it comes to transmission oil. Yes,they  do have a function on website for engine oil and nothing else.I reach out to them a couple of days ago and I am waiting for a reply.As a man that totally brought a Boxster back to life after a rollover I am pretty good.I was responsible for all recalls,because Porsche wrote me off.Right now I am going to Redline which has a lot of information regarding my car.

[boxstermuscle]

Hi Tom,

 

Your vehicle calls for a GL-5 75W-90 oil for the manual transmission,  We don't know for sure if the LS additives can be used.

 

A safer choice would be our Mobil Delvac 1 Gear Oil 75W-90

 

I Just received this reply from Mobil

[JFP in PA]

It is your car and your money, and you are the only one that will have to deal with the outcome of that decision, but the car does not use a GL anything oil, regardless of what the boys at Exxon tell you..........................

[Silver_TT]

Redline???  That's exactly what ruined my gearbox.  It's your car and your money but I don't want something bad to happen to you like it did to me -- you really need to be careful here or this is what you could have in store in your future:

 

Edited September 14, 2021 by Silver_TT

[boxstermuscle]

Thank you Silver_ _TT and JFP for your valuable information.I guess I'm going with the Porsche Stuff.I was going to try Mobil 1 Delvac if I couldn't get the Porsche Stuff.Thank You Guys

[JFP in PA]

33 minutes ago, boxstermuscle said:

Thank you Silver_ _TT and JFP for your valuable information.I guess I'm going with the Porsche Stuff.I was going to try Mobil 1 Delvac if I couldn't get the Porsche Stuff.Thank You Guys

 

Contact board sponsor Sunset Porsche, they have a great website and carry it in stock.  The factory stuff is full synthetic and has a long life. 😉

[Silver_TT]

+1 Sunset Porsche is an excellent site

 

p.s. I see you're in Brooklyn.  I used to live in Clinton Hill.