Changing 355 gear oil step by step by butch355

By diyauto
( 1 )

Changing 355 gear oil step by step

Compliment of butch355 @


Well after searching the forum on all the gear oil posts I didnt see one on step by step changing the gear oil. First off I am no expert and will share everything I learned from this little adventure. I posted a similar post on 355 oil change but didnt post pics sorry. I know this might seem easy to most of you, but some of us are a little gun shy of tearing into a $80,000 car!! Hope this helps!

First off you will need a set of large allen type heads that attach to your socket for the drain and fill pug. (Harbor Frieght) $10.

You also will need a long funnel to get the oil into the gear box (any tranny funnel works good!)

Something to collect the gear oil.

And finally the gear oil. I used Redline Lightweight Shockproof $10-$15 per quart (Many other posts on this topic). I talked to the dealer (FOD) and he said to be safe add some limited slip additive. I used the BG additive $10. My car used 5 quarts of the oil and the additive to get the perfect fill mark.

First off drive your car or get it up to temp to get the oil warm.

1. You will need to remove the drivers side air filter box to get access to the filler plug and dip stick (need one of those large allen heads). I would do this first to make sure you can get it off because mine the dealer put on with so tight I had to use my AIR TOOLS to remove. Kinda tight in there and I couldnt get enough leverage to get the damn thing off. THANK GOD the air tool broke it loose! Also, be careful taking off the air box not to loose the washers and the nuts, they are small!!

2. Raise your car to get access to the drain plug. A lift works great but I assume you could jack the car up if the car is level to get all the gear oil out. Let the car drain for a good 10 minutes to get all the old oil out to be safe. Replace the washer on the drain plug also if it looks worn at all.

3. I would replace either of the plugs if they show any wear or stripping. Some trucks I own I change them out every diff change per manual to be safe.

4. You can lower the car now to get better access to the fill area and add at least 4 quarts of oil then check the dip stick. One more quart should be right in the safe area and others might take one more. If you add the limited slip additive I would to that first.

5. Putting on the fill plug was kinda tight and then clean up the overspill. Luckily the mess isnt too bad because the oil leaks straight to the floor.

6. Put the air filter back on and test it out.

My car shifted ok before I changed the gear oil out and I now the car does shift much better and a major difference. I now make the gear oil a anual event with the oil change no matter how much I drive it.

Good luck

First photo is the top fill plug under the air box

Second photo is the drain plug

Third photo is special allen set needed from Harbor Frieght or any auto store

Last photo is the oil and additive I used.