What type of transmission fluid is reccomended for use in a TH400 Switch/Pitch with 4500 high stall running low 11's to mid 10's? Dextron? Type F? Other? My car has 464 and currently runs 11.2's in the quarter. I was told by the builder of the converter to use Caterpillar 30wtTransmission/Drivetrain oil and that is what I've used for the last few years. The only thing I don't like about it is that the car won't move until the fluid heats up, once it's heated up some it drives and shifts good. I'll be changing the fluid soon anyway and was wondering if there is something better to use. Thanks, Ken
I have read many articles on trans fluid and as with newer motor oil the new dextron is not what it used to be. Modern transmissions run much cooler than our old turbo 400's and the new stuff is just not up to snuff and will make your trans run hotter. Most sources recommend a good synthetic trans fluid such as Mobil-1 auto Trans fluid. B+M also has a good synthetic trans fluid. I have used the Mobil-1 for years and had a Trans shop guy I know do a tear down for a check and he said it still looked new inside. This is after about 30,000 miles. Of couse chainging the stuff every two years can't hurt either.
That's good information, thanks. Anyone else have any suggestions? I've always used Dextron in the past without any problems and still use it in my other cars. I was told that at the power level I am at that the Cat. oil would extend the life of the trans but I just don't like the way it is when it's cold so I really don't want to go back to it, plus it's not easy to find around here and you have to get it in 5 gallon buckets when you do find it. I may end up going with the Mobil 1 synthetic like suggested but I'd like to see what others have had good luck with too. Thanks, Ken
Ken, I always heard that the Cat oil was great for a switchpitch, but I believe it comes in different weights. Which weight are you using? As for me, I use Red Line Synthetic D-4 in my SP. "Synthetic Dexron III and Mercon Fluid meeting the requirements of most transmission manufacturers. Superior stability allows high-temperature operation without varishing valve and clutches. Also provides tremendously improved shifting in cold weather. The best low-temperature shiftability for manual transmissions and transaxles which require ATFs."
Trans fluid I recently did a filter change on my TH400 and used Valvoline DexronIII/Mercon. I assume to use a synthetic you would also need to change out the fluid in the torque convertor?
You know what they say about the word Assume :laugh: By law, all engine and transmission oils must be compatible. Nothing wrong with mixing regular oil and synthetic. To get all of the oil out of the trans, you would need to remove and drain the converter.
Regular transmission fluid On the topic of regular transmission fluid, I would "assume" the newer versions are better than the ones from say 10 -15 years ago. Do they also have ratings similar to motor oils? Thanks. Mitch
My converter has a drain plug installed in it so it's not a big deal to drain it too. It looks like I may be pulling the trans anyway to replace the s/p solenoid which I think that I have to remove the front pump to get to. I'll be doing a filter change at the same time also. Ken
I was told buy my s/p converter people to use type f fluid is this wrong and will it damage the trans.
Id ask Jim over at PAE Can't think of his user name here off hand. He is the switch pitch guru. On my Th350 he built for me he said a good syn, I used royal purple racing syn. Cost a fortune even ina 5gal jug and my only problem was its hard to read on the stick. I would of probably went with RedLine racing syn if I knew it then. http://www.paeenterprises.com/
Back in the day I was told that I could run a TH or ST400 with Type F, but only if Type F is what the transmission had seen previously; i.e. used during assembly of a rebuild. I understand that back then, Type F and Dextron II were not compatible, so switching after the fact was a no-no. I don't know the status of compatibility between Type F and the later Dexrons today. What fluid has the transmission seen in the past? Or if a rebuilt unit, what fluid was used during assembly? Devon
Larry, What Law? A law of Physics or something else! Each transinnion manufacturer can engineer whatever they think will give them an advantage in the performance, driveability, durability and servicabiliy fields. I woouldn't think of putting 90tw gear oil in my TH400 but it works great in a 75 year old John Deere tractor. I won't go into the required fliuds for the Allison trans in a GM truck, the CVT fluid for a Nissan, the Synthitic in a F -series Super Duty with a Torque Shift trans: I'll stop now.
I think you missed the context of Larry's comment. What he's saying is that for a mineral-based lubricant meeting the specifications for a particular application, the synthetic equivalent will be compatible. For instance, the American Petroleum Institute (API) regulates motor oil standards and compatibility. The idea is that simply mixing a synth with it's equivalent in mineral based stuff is not going to turn it to jelly or anything. Back when the synthetics came out, everybody screamed "no compatbility!" because they just didn't know better. Now they even market the stuff already blended. I posted because of the question that came out more recently which wasn't related to mineral vs synth compatibility, but rather using a lube not originally spec'd for an application. The big OEMs seem to have been pretty wierd with their own specified transmission oil requirements, which is why I can't positively tell someone to switch a trans running Dexron II to Type F...I don't know what will happen when the two get together, which is inevitable even with having drained the former fully. I've run Type F in some Hydramatics in the past, but they started out life that way - so I had no issues with the two different types of fluid interacting. Devon
Not the law of physics, I believe it is Federal law, but I might be mistaken. My point is, I've heard people talk about synthetic oil like it was something so different from mineral based oil. It really isn't. Mineral based (Dinosaur) consists of many different types of molecules. Some are better at resisting heat and are more stable. They are all, obviously compatible. Synthetic oil is man made oil, consisting of the very best molecules to give you the best protection. Synthetics flow better, lubricate better, are less affected by extreme heat and cold temperatures. Synthetics will mix just fine with any mineral based oil, because it is oil. Additive packages will vary from one brand of oil to the next, but the bottom line is you can mix them without any problem whatsoever. N360LL, you missed my point completely. I'll stop now
Larry, your point is valid about the API and SAE by extension. Sorry for missing the intent of the comment. That said, a lot if engineering time and money is spent on "testing" fluids before a manufacturer releases a new technology that will make the lives of the owner/operators "better." As to the original question as to which fluid to put in a TH400 with a high stall converter. I referred to the Ron Sessions book and note that on page 217 there is a chart depicting the differences in Coefficient of friction and Engaugement Time between Type-F and Dextron II. There are also sections in the book that talk specifically about the pro's and con's of various fluids that were available at the time the book was written (1987). With all that said, I have run CAT 30wt in my SP TH-400 since is was built 13 years ago without any problems. I run it in my non-SP TH-400 with a 2400 stall convertor because I want consistancy in applications for my GS's. My TH-400 in the Jeep gets Dextron III. The C-6 gets Type-F and the 727 gets ATF+4 per the owners manual. I chose the CAT fluid after research, consultation with PAE, transmission technicians and the fact I could get it locally without any issue. A benefit of the CAT fluid is that the trans temps are lower than compared with Dextron at similar loads. I also notice that the operation seems a bit more definitive with CAT vs Dextron ( when it shifts you feel it). My experience tells me that this is due to the viscosity at the temp and pressure that the trans is at in relation to the tolerances internal to the transmission. One con is that it is almost the same color as the engine oil I run. So, any seeping is hard to find the source of without some serious investigation.
Not long ago, I was contacted and repeatedly asked to help the guys on a caddilac board out with some VP converter stuff. After a while I went over on that board and gave some info, that has never been posted here. This thread contains the picture as to why one outfit wants you to use high viscosity transmission fluid in their converters. It's the first picture in reply number 31 on the second page. My input to these guys on the issue at hand is on the third page. Here's the thread http://www.cadillacpower.com/forum/index.php/topic,9394.0.html To see the pictures, you will need to log in, you can use my username and password, which is Tsp Jim (make sure you put the space in) 1970stage1 Plenty of other pictures on there, and I have no issue pointing folks to this board to see this issue, as I had no hand in creating the thread, or bringing the issue to light. If you have a correctly modified VP converter, there is no need for any special high viscosity fluid.
I asked jim at PAE he replyed "would use at least type F. The best fluid I have found is caterpillar transmission drivetrain oil available through a caterpillar tractor dealer, part number 8t-9572 in 30 weight. I have found this to be the best fluid for these, and the transmission as well. It mixes with any other atf as well. Jim Dave 72 GSX restoration 90% done
Thanks for the good reading, Jim. Pictures are worth 1000 words...I can imagine what the turbulent flow would look like in there. FYI, I have yet to disassemble the VP converter I got from Texas. I'll let you know when I've had a chance...maybe I can harvest the stator at least, but then that may not be any good either, from what I've just seen. Devon P.S. I'll be sticking with Dexron, thank you very much.
