Gearbox oil advice

A5/S5/RS5
#1

Hi All,

Just looking for some advice really.

Just about to service the RS and I’m considering doing the gearbox oil.
I’m not sure when it was last done but just wondering if there is anything I should know or be warned about first.

Cheers in advance

#2

I use redline and have always been very happy with that. The friction modifier I feel is a big help. On the DSG units make sure to change the filter I think there’s two of them for your unit.

1 Like
#3

First I’d start with Ape’s writeup on Audizine, here is the link:


I used Redline DCTF in the ATF side of the transmission and Redline 75w-85 in the MTF side. You will need the 2 filters, pan gasket (can find aftermarket a lot cheaper than Audi), and all of the bolts for the pan are stretch bolts so they are supposed to be one time use and replaced.
His writeup also covers the rear Diff.
Being Anal I also replaced both of the transmission drain plugs and the two rear diff dtrain plugs with Magnetic plugs from ECS.
Also, you will need VCDS or one of the other VAG specific readers to monitor the temperature (fill level) correctly. There is a purge procedure for the rear diff, many have done the service without it but you can do it like the dealer with Vagcom or just fill it, drive it a short distance and then recheck the levels.
#4

I drive in a figure 8 after servicing the diff. I also prefer the “measurement method” where I measure the amount that came out and put that back in. This negates a lot of the pain in the ass steps for filling the transmission, particularly on the ATF side.

I prefer Motul Gear 300 as it has a higher VI index than almost anything out there outside of uber expensive race gear oils. Use the regular Motul 300, not the LS version.

1 Like
#5

The figure 8 would be good to do as it would get the clutches to engage/disengage, especially under a little power. Motul 300 does have good numbers. I’ve never been a fan of the measure the drain and refill method as all oils, less so with Synthetics, have an Evaporation percentage. Many manufacturers don’t print their numbers, some do so it is hard to compare numbers. With the Transmission/Diff intervals and of course using Synthetic oils it probably isn’t too much of a factor.
Besides the improved Lubrication property improvements of top quality Synthetics, I remember getting TSB for my old Audi 200 that required going to the dealer and swapping out the Dino oil in the transmission to a Full Synthetic due to the lower Evaporation properties. Once the TSB was complete they gave you a manual insert that deleted the Transmission service interval to Lifetime, still a stupid idea.

#6

Thanks guys. Someone mentioned 2 filters which I’ve found is correct. Getting a garage to quote both instead of just one is quite hard.

I do have someone that can do it for me though so will get it done in coming weeks

#7

Yorkshire_mick, the reason for that is Audi normally only specifies to remove and replace the externally mounted tubular shaped filter in the fluid cooler line when servicing. The internal pan filter is only to be replaced when opening up the transmission for servicing, ie Mechatronic replacement, Solenoids, etc… Pretty much every DIY’er does both evertime. Keep in mind you will need the two filters, pan gasket, and Audi specifies that the pan bolts be replaced everytime as they are stretch bolts. I’ve reused them once on my S5 with no issues and will put new ones in next time. I was in no hurry on the RS5 so I installed new ones. Also need Vagcom or something similar to monitor the temperature for the right fluid level.

#8

I found that temperature monitoring is unnecessary if you’re working with a cold engine. Having changed fluid and filters in both Audi DSG and BMW DCT, I’ve seen that you should run the car for less than about 5 minutes while adding fluid until it drips out. Right before I close the fill port I squirt another ounce or so in and quickly close the cap. I was curious while working on the exhaust and cracked open the fill cap and it started dripping. I’ve never had problems.

#9

From a cold fill I find it usually takes at least 15min of running to get the transmission up to the correct temperature.

#10

I don’t have the media in front of me but don’t they ask that you simply not cross a temperature threshold rather than wait to meet a required temperature?

#11

Thanks Hahn.

Yes one of guys that can do for me said to spend the extra and do it all in one go. I’m in no major rush and will get them to do it for me next month hopefully

#12

This is how the manual reads:

When ATF reaches temperature of 30 ℃, unscrew ATF inspection plug -arrow-.
• The ATF level is correct if a small amount of fluid comes out at the ATF inspection plug when the ATF temperature is between
30 °C and 50 °C. If this is not the case, top up ATF ⇒ page 149 .

1 Like
#13

Yhats the way I’ve understood it and always done with no problems !!

1 Like
#14

I’m such a nightmare ain’t I Steve with all my questions haha.

1 Like
#15

The quotes I gave are from the manual for checking the fluid level. The same temps for filling. With the engine off you fill until the trans pan is full, start the car and start filling again. Once full you let it drip until the internal temp is 30~50’C. Pretty much with any Automatic transmission they can tolerate a little overfill better than an underfill. I never let it get past 40’C, usually cap it off by 35’C.
In RS5’s technique the transmission will be a little overfilled. Some may eventually vent out of the transmission as others have seen doing a lot of launches and getting the DSG hot, and without a transmission Cooler such as Redmist Racings to keep the fluid cooler you are more likely to get a little more foaming if driven aggressively (think launches, track days, etc…) This applies to almost all newer Automatic transmissions and the fill procedures are pretty much the same for ZF, BW DSG, Aisin, Mercedes, with only the final temperatures a little different.

1 Like