The 1989 Porsche 928 S4 with the automatic transmission uses a Mercedes 722.3 Transmission. I was having problems shifting from drive to reverse. I would actually sometimes turn off the car then put the car in park, turn it on again and then into reverse. The transmission was rebuilt, I replaced the vacuum modulator, governor as well as rebuilt the valve body with a shift kit.
The Porsche Community only has a few transmission gurus. So, I started doing research on Mercedes forums and found out the Neutral Safety Switch was the problem. I could not find replacement instructions on any Porsche forum so I ended up using an article written by a Mercedes mechanic. The process was very simple. I already had the exhaust removed to make space and the car jacked up in the air. I only had to remove 2 bolts and disconnect the shifter cable. I was surprised on how simple and expensive the part was but it obviously worked because it prevented me from going into reverse.
Several automobile manufacturers are claiming their vehicles transmission fluid never has to be changed. I talked to both engineers and experienced mechanics, all of them said that is impossible.
What I did find out was many vehicles warranties typically are over after 3-5 years and around 100,000 miles. I have read several reports of owners of these vehicles that have never changed their transmission fluid going to the dealer after the warranty is over just to find out they need a major repair on their transmission. The majority of transmission repairs require the transmission to be removed from the vehicle. Several vehicles also require the engine to be removed so the transmission can then be removed. This is very expensive. Since the warranty is out, they have to pay the bill themselves.
My 2017 Toyota Tundra’s Maintenance Manual did not really give a specific interval on when to change the transmission fluid. I only found sections that said, “inspect for leaks”. Some Tundra Dealers seem to have gone against the maintenance manuals and advise getting the fluid changed around 50k-65k miles. I decided at 55,000 miles to change the transmission fluid. I used AMSOIL Signature Series Fuel-Efficient Synthetic Automatic Transmission Fluid. I had to watch several YouTube videos to find out how to change the fluid on the Toyota Tundra. Some things that make this hard is there are multiple transmission models for this year.
Basically, I drain the transmission pan. I removed the transmission plan to clean it and replace the transmission filter. I then re-installed the transmission plan. I then added the amount of fluid I took out. I then had to disconnect a transmission line that goes from the cooler to the pan. I made this line go into a drain bucket. I then had to put a pin in some kind of thermostat to make sure all the fluid drains from the transmission cooler. I would start the tundra for a few seconds until 3 quarts was removed. Then I would add 3 quarts of new fluid. I kept doing this until all the old fluid was out. One of the hardest parts was adding the correct amount of fluid. You basically have to make sure the transmission fluid is in a certain temperature window then look at the flow of fluid coming from one of the plugs you took out. I burned my hands doing this. I also got bit by fire ants because I had to do this in the street (level-surface). You would think there would be a simple dipstick but Toyota decided to make changing the fluid difficult. I really did not trust anyone to change the fluid that’s why I did it myself. A lot of people will just drain what is in the pan and not the entire transmission system. I put 10,000 miles on my Tundra since changing the fluid, there is no problems. It shifts a little more smoothly than the stock fluid. I wish I would have changed the fluid when I first bought the vehicle. This synthetic fluid has outstanding wear protection.
Here are some of the specifications the transmission fluid meets or exceeds (AMSOIL also sells CVT and dual-clutch transmission fluid).
AMSOIL Signature Series Fuel-Efficient Synthetic ATF is recommended for transmissions and other applications that require any of the following specifications:
Aisin-Warner AW-1; BMW 83 22 0 142 516, 83 22 2 152 426; Chrysler MOPAR* 68157995AA, SP-IV, 68218925AB; DSIH 6p805; Ford MERCON* LV, SP, ULV; GM DEXRON* HP, DEXRON* VI, ULV; Honda/Acura DW-1*, Type 3.0; Hyundai/Kia SP-IV, SPH-IV, SP-IVRR, NWS-9638, SP4-M; JASO 1A-LV; JWS 3324; Mercedes Benz 236.12, 236.14, 236.15, 236.41; Mitsubishi SP-IV, ATF J3, ATF-PA, ATF-MA1; Nissan Matic-S, Matic-W; Saab 93 165 147; Shell M-1375.4, M-1375.5, M-1375.6, M-L 12108; Toyota WS; Volvo 31256774; VW/Audi G 055 005, G 055 162, G 060 162; ZF S671 090 255.
AMSOIL Signature Series Multi-Vehicle Synthetic ATF is recommended for transmissions, hydraulics, power steering systems and other applications that require any of the following specifications:
Allison C-4, TES-389; BMW 7045E, 8072B, LA 2634, LT 71141; Chrysler ATF+4*, MOPAR* ASRC, 68089195AA, 68049954AA; Ford MERCON*, MERCON* V, ESP-M2C166-H, FNR5, M2C924-A, XL-12; GM DEXRON* II, DEXRON* III, AutoTrak II; Honda/Acura ATF-Z1; Hyundai/Kia SP-II, SP-III, Red-1; IDEMITSU K17; JASO 1A; JWS 3309,3314, 3317; MAN 339 Type V-1, 339 Type V-2, 339 Type Z-1, 339 Type Z-2, 339 Type Z-3, 339F; Mazda ATF-M III, ATF-MV, F-1; Mercedes Benz 236.1,236.2,236.3,236.5,236.6,236.7,236.9,236.1,236.11,236.81, 236.91; Mitsubishi SP-II, SP-III, ATF-J2; Nissan Matic-D, Matic-J, Matic-K, 402; SAAB 3309; Shell 3403, LA 2634; Subaru ATF, ATF-HP; Suzuki 3314, 3317; Texaco ETL-7045E, ETL-8072B, N402; Toyota Type T, T-II, T-III, T-IV; Voith 55.6335, 55.6336; Volvo 97340, 97341; VW/Audi G 052 162, G 052 990, G 055 025; ZF TE-ML 03D, 04D, 05L,9, 11A, 11B, 14A, 14B, 14C, 16L, 16M, 17C, 20B, 20C, 21L.
