I recently had my 4r100 fully rebuilt and now have decided to go ahead and ad the 3.5 quart bigger trans pan since I do a lot of towing. Anyway my question is if it would hurt anything or even have any benefit if I put royal purple in when I change the pan. Due to the trans and system only being a few weeks old I'm not doing a full flush so I know it would be mixing fluids merc v and royal purple.

 

I'm curious, why you think changing the OEM pan for a pan that holds more fluid will help you when it comes to towing?

All a bigger pan will do is cost you more money because it takes more fluid to fill. It doesn't provide any extra protection for the trans, nor does it help with keeping the trans fluid temps down.

It is great for looks though!

Stewart

 

I wouldn't mix half Royal Purple with half Mercon V. All or none.

 

X2. Why would you do that?

Larger cooler up front is FAR more beneficial. A larger pan is sales hype only, and was proven in Ford's trans lab. You end up with more hot oil, which also takes longer to cool back down.

So why?

Pop

 

I would not mix synth and merc v fluids.

 

Ok, I will throw it out there because I use one and it works just fine or me The argument often includes heat this or heat that; however, here is my 2 cents worth of the argument. I use a mag-hytec pan that gives me a little over 8 quarts above stock levels. Now the reason I say this works is that you need to use a deep pan in addition to a larger cooler. More fluid may take longer to heat up but its not much of an issue with cooling the fluid down if it does not get too hot to begin with.

Now stay with me for a second. Using a good cooler keeps the fluid cooler so when you do pull up a hill here and there, it takes longer for the tranny to get hot and that may be all you need to get up and over that hill. Once you are going down or back on straight driving, the larger cooler is more efficient at bringing the fluid temp back down quicker than a stock setup and returning to cooler running temps. I think this argument is often based on extremes and not regular conditions. I don't worry about having to wait for my blistering temps to drop while I sit on the side of the road as I would not put myself in that situation.

I have pulled large boats on occasion but I have not driven it to the point where I need to wait for anything to cool down so I could continue down the road. Basically, if the temps stay down and it takes longer to heat up on the hills then the combo may show some bennies. This argument goes right along with others that argue removing this or modding that makes a diffrence when others argue that the mods have no sigh of improvement. Now, I will sit back and take the thrashing that is sure to follow but that's OK, everyone is allowed their own paradigm.

 

No way I'd mix fluids. Just a drain and fill would leave plenty in the torque converter, for example. Mercon V is fine. I doubt you'd ever notice a change if you switched to Royal Purple. I agree with everyone else on that point. Now I'll throw out a few related links and opinions.

You will definitely notice a difference towing with a 6.0 trans cooler. If you plan to tow increased trans cooling is mandatory, IMHO. See size differential oem 7.3 vs oem 6.0 in pic. Plus the tech is different, so the benefit is greater than the size difference. Drops into same mounting holes so install is pretty easy. You can find cheaper options, but none are better. I run that plus a Magnefine filter.

The OEM dash trans guage is not effective. By the time it shows hot you're mostly cooked. A real trans gauge was my choice, but various scan gauges can get the job done if you prefer that form factor.

I like the added volume of trans fluid provided by a deeper trans pan, for the same reason I like an engine holding 4 gallons of engine oil. Oil stays fresh longer in normal service since there is more of it. Of course, once the clutches get to slipping and burning up the added volume is of no benefit. I don't think a deep pan has any big impact on trans fluid temps. All that said, if you like it, run it.

What do you tow?

 

You say that as if MERCON V wasn't synthetic. How do you know? You can get MERCON V that is conventional, blend, or full synthetic. So your statement just doesn't make sense.

Not EVERYONE else. I don't agree with this point.

You've just made a good argument for a better cooler. You haven't shown me ANY reason why I'd want a larger pan. If you have a better cooler then the trans isn't going to get hot with either the stock pan or the larger pan.

If you have to pull off to let the trans cool down one of two things are happening. Either you're one of the people that gets scared when the trans gets over 200°F and pull off needlessly, or your truck doesn't have adequate cooling. I can't fix the former, but the latter is easily fixed with a larger trans cooler.

 

i have stock trans and pan. i pull heavy the load will be 6.25 tons not counting the trailer gcw = 24,000lbs. and it is hot here but with the 6.0 cooler i never see over 195*. i see no need in more fluid but a better cooler.

 

My experience as well.