Fluid for a TH350

[Hawker7]

I just put my rebuilt 350 trans in and need to get some fluid. What are you guys using? Synthetic??, or I see that Castrol makes some for older transmissions. While mine is newly rebuilt I don't know if it falls into that category?? David

[Longhorn Man]

if you have the coin, you simply can't beat synthetic. I have mobile one in both of mine after getting them rebuilt.

[Hawker7]

thanks, Andy. How often do I need change it after putting in synthetic? I will probably only drive it a few thousands miles a year, so I guess time will be the only factor. I don't mind spending the extra money if it will last a longer.

[Longhorn Man]

if you arent towing big loads, or driving it real hard, then I would pretty much say 50,000+ miles. Assuming the tranny lasts that long.
It hurts when you drain $100 worth of oil out due to tranny issues.

[mbgmike]

I bought a new Corvette Convertible in 1986. Just for info I added a bottle of Slick 50 trans additive in it. I was never sold on additives much and did not want to add it in the motor. I sold that car in 1995 with 287000 plus miles on it. Three paint jobs one motor rebuild and other parts replacements BUT the tranny was never touched except for filter changes. I know slick 50 isn't around but there are some other additives out there. All I know is that it sold me on them.

Mike

[Longhorn Man]

while i can see why you are sold on it, my tranny guy can talk to you for an hr on why you shouldn't use them on a good tranny, and he is well known through central and western ohio as THE guy to go to.

[Hawker7]

I have decided to get synthetic fluid and found Mobil 1 for around $8 a quart, and Valvoline for a little over $5 per quart. Is there any difference between the two besides the price?

[Longhorn Man]

unless you talk to a lab, you'll only get speculation and brand loyalty for an answer.
My speculation says they aren't the same, and my brand loyalty says go with the mobile one.

Either way, they are both a quality product, and WAY better than conventional fluid.
Basicly, you can't go wrong between the two.

[1970bowtie]

type f

[turp mcspray]

Originally Posted by 1970bowtie

type f

My thoughts exactly. I've used type F for years. There is a noticeable difference in shift firmness.

[Longhorn Man]

Fluid causing firm shifts means it is thicker and causing the pump to work harder.
I have heard many tranny guys say F is a better fluid, but they always said NEVER mix F with dextron.
Even if it is better, and if my assumption of the added pump wear was bogus, it stilll cant beat a quality synthetic fluid.

[turp mcspray]

Originally Posted by Longhorn Man

Fluid causing firm shifts means it is thicker and causing the pump to work harder.
I have heard many tranny guys say F is a better fluid, but they always said NEVER mix F with dextron.
Even if it is better, and if my assumption of the added pump wear was bogus, it stilll cant beat a quality synthetic fluid.

I have a friend that owns a large tranny shop. One time when I was over there They were putting fluid in something and I noticed they were pumping it out of a large tank of about 4000 gallons. I asked if they have a large tank for all different types of fluid. He said that all fluid (ford, chrys,or gm) was the same except for the additives each one uses. They fill the tranny then add the correct additive. I knew type F had a different friction coefficiant but that was about the extent of what I knew about it. If you ride in an old ford they always shift firm. Gm makes there stuff shift smooth. To me smooth equals slippage. I have reasearced this a bit and found nothing to say stay away from F. I tend to not rely on a single source for any info. Too much opinion. But if 8 out of 10 say the same thing I will usually take it as good info. I hope I don't come off as a know it all type. I am an information whore so to speak and like to share things that I come across in my never ending search for more info.