What To Do About Trans

[natesimpson74]

I just bought a 99 1500 nsb, 5.3L auto. It currently has 128,000 miles on it. The guy I bought it from said that he had the trans fluid changed at about 100,000 miles but he wasnt sure of the exact mileage. I have already switched the rest of the fluids over to synthetic and am nervouse about doing it in the tranny.

 

Would it be safe to pull off a trans cooler line to get the old fluid out and add synthetic? I know it can be done, I am just worried about the mileage and starting to have problems with the tranny. Shouls I just change the filter and use regular trans fluid?

 

What would you all advise for me? Thanks in advance.

[Ranger]

You can just drop the pan and then top it off again (AFTER draining the pan and reinstalling it of course)...Otherwise yes you can use the cooler lines to flush it...Just make sure you got plenty of ATF in the bucket.

[natesimpson74]

Im just afraid that adding too much fresh fluid into the system might break apart some gunk and ruin the transmission. Thats why I'm asking to see what experience others have and if they think that it would be adviseable to flush it with cooler lines or just drain, change the filter, and refill. Is it worth it to go to synthetic with 128,000 miles on it already?

[Ranger]

Flushing it will do that, just changing the fluid via the pan will not. If they already changed it then you're good to go for a while longer...Just look at the trans fluid dipstick and see how it looks.

[ColoradoSkiCountry]

If I remember correctly, the Tranny Fluid from the factory in a 99 was a high quality fluid, I don't think you would be doing any damage by switching over to a full synthetic, or if you are not too sure, a good synthetic blend.

[CapitalTruck]

In '99 they were using Dexron III, now they use Dexron VI which is a synthetic fluid. Dexron VI is safe to use in Dexron III applications, so, I would imagine you would be okay using a synthetic.

 

 

If I remember correctly, the Tranny Fluid from the factory in a 99 was a high quality fluid, I don't think you would be doing any damage by switching over to a full synthetic, or if you are not too sure, a good synthetic blend.