2003 Chevy Express 4.3 Need oil Help

[Josh0121]

I have a 2003 Chevy Express Cargo van with the 4.3 V6 and the 4L60E transmission. It has 61k light duty miles currently. I bought this van to put it on a delivery rt. It will be driven 250 miles daily mostly all highway making a few deliveries to Dealerships etc..

This is the first time I will be using a vehicle to this extreme. Any advice on oil/filters transmission fluids etc..!

I currently had the Transmission fluid changed and also the oil with Mobil 1 Full Synthetic 5w30 for Truck/SUV. I also used a fram tough guard and 3/4 bottle of STP oil treatment. I will also be running lucas Upper cylinder lubricant..

Any help or advice or fluid intervals Transmission /Oil etc

Thanks guys!

 

[The_Jeff]

Dump the STP and Lucas.

What's your rear axle ratio? I bet that 4.3 will be spinning most of the time. This means great pressure even on 5w30.

I'd consider an external transmission cooler, just a cheapie, and dexron VI, it's a synthetic (blend?) and very very good. Dump your Dexcool or watch it like a hawk, and your rad cap as well. Cooling and trans problems kill more cars than engine trouble. If you have a belt driven fan consider changing it to an electric one; your highway MPG will improve as the ram-air will be more than enough to keep your rad cool.

Go with whatever 5w30 oil and a cheap, non-fram filter. Or, if this means lots of downtime, keep the M1 and something fancy like a PureOne, presently on sale on amazon and at Advance after coupons (see the rebate section.)

 

[Chris Meutsch]

I would go all Amsoil if money isn't an issue. 15k-20k oil, and if you completely change the fluid out in the A/T, 50k-75k on that fluid.

If money is, PP/Mobil 1 5w30 in the engine for 10k runs and GM transmission fluid for whatever the change interval is.
I would also go with a PureOne filter.

***All statements posted above are my opinion and definitely reflect so.***

 

[Josh0121]

3.73 Rear Axle Ratio, Speed limit is mostly 55 to 65 so it does not wind up that high of an RPM. Is it difficult to install a external transmission cooler? Never installed one before. I know I had seen the lines coming up to the radiator, do I just come of those lines?

 

[The_Jeff]

http://www.summitracing.com/parts/FLX-3820/

Typical install is to cut into the hot ATF line going to the rad so you cool it off some then the rad stabilizes it, and even sometimes warms it. Alternately you can cool what has already been cooled in the rad. But there's such a thing as "too cool"; I wonder if your trans has a thermostat for that.

I just picked that midsize cooler out of the blue; they have smaller and larger ones. However I do think you have 3/8" lines and it has 3/8" barbs. You stick it to the front of your radiator with those fancy zipties.

 

[Josh0121]

Thanks for all your help and input. Its nice to have a forum like this!

Also is there an easy way of telling which line is the hot and the return other than feeling it while running?

 

[tomcat27]

ditto on losing the STP and the Lucas. I personally like synthetics - especially for the type of service you are proposing. don't forget to change the coolant - dexcool has a big history of eating away at intake (and head) gaskets when it gets old. I also like transmission coolers - altho you are not proposing any towing....

 

[Josh0121]

Should I drain the oil and replace without the stp or will it be ok until my next oil change.

 

[sr17]

Rotella T6 5W40 and PureOne filter seems to work very well in my Astro - which I believe has the same engine and transmission, someone please correct me if I am wrong?

My van is used a lot for heavy trailer towing and short trips around town.

I installed a transmission cooler and service the transmission every year.

Over the last 18 months I have also used MMO in the tank pretty consistently

yes I know that is a controversial decision, but there are many on here who believe it is a good thing.

 

[pavelow]

Originally Posted By: Josh0121
I have a 2003 Chevy Express Cargo van with the 4.3 V6 and the 4L60E transmission. It has 61k light duty miles currently. I bought this van to put it on a delivery rt. It will be driven 250 miles daily mostly all highway making a few deliveries to Dealerships etc..

This is the first time I will be using a vehicle to this extreme. Any advice on oil/filters transmission fluids etc..!

I currently had the Transmission fluid changed and also the oil with Mobil 1 Full Synthetic 5w30 for Truck/SUV. I also used a fram tough guard and 3/4 bottle of STP oil treatment. I will also be running lucas Upper cylinder lubricant..

Any help or advice or fluid intervals Transmission /Oil etc

Thanks guys!
If it were mine, I would run Shell Rotella Syn 5W40, Purolator Pure 1 filter and no STP. Change it every 5K. As for the transmission and rearend, change the the trans fluid/filter and rearend lube every 30-40K. If you wanted to be more cost effective with your lubrication schedule, have your engine oil, transmission fluid and rearend lube sent out for oil analysis and they'll let you know where you stand on a change interval.

And don't forget about the antifreeze. I'd change it every 40K miles.

As for the transmission cooler install, some transmissions have in and out stamped on the trans case where the lines attach to the trans. If not, a Haynes or Chilton manual will tell you what line is what. If you do the external cooler install, make sure you double up the hose clamps on those rubber lines.

 

[pavelow]

Originally Posted By: Josh0121
Should I drain the oil and replace without the stp or will it be ok until my next oil change.
I would. You really don't need the STP in there.

 

[beanoil]

Originally Posted By: Josh0121
Should I drain the oil and replace without the stp or will it be ok until my next oil change.

Nope. Just don't use it next time. A trans cooler is always a good investment. Those 4.3's will run forever on nearly anything. My sis in law has one with 285k on it, always serviced a the local Walmart while she shops, with whatever the cheapest change on the menu is. Any name brand conventional would be fine in it at 5000 mile intervals. But if you insist on a synthetic, I second the Rotella 5w40 recommendation above.

 

[addyguy]

Leave the STP/M1 mix in - would be a complete waste to drain it.

Maybe you don't need it, but that doesn't mean it will hurt the engine - it won't.

Like others have said, Rotella T6 5W-40 would be a good oil for this engine.

 

[oggb]

I'm pretty sure Rotella T6 works great in everything.

Then again a GM 4.3L is probably going to die a horrible, dexcool related death LONG before anything oil-related happens to it.

And yes, external ATF cooler +1,000. Especially for such a problem transmission.

 

[NMP]

Originally Posted By: beanoil
Those 4.3's will run forever on nearly anything. Any name brand conventional would be fine in it at 5000 mile intervals. But if you insist on a synthetic, I second the Rotella 5w40 recommendation above.

What he said. I ran 25 Astro vans with 4.3 engines and never had an engine problem with any of them. Highest mileage was 248k.
I never changed the coolant on any of them. Dexcool seems to be a problem on 3.8 V-6s (gasket material issue)and S-10 trucks (Coolant cap allows air in system).