GM recommends an AC Delco oil filter SIZE of PF 47 for the two wheel drive models and the PF 52---longer =more capacity---- for the 4WD models. They are the same price usually. I like the bigger PF 52 size and all oil filter manufacturer will have the conversion table for their brand. I recommend Wix premium brands oil filters and NAPA Gold oil filters I understand are also made by Wix. Please don't use Fram oil filers per BITOG.com forum.

 

Is there any harm in having the "Coolant Overflow Reservoir" or "Expansion Tank" (also called a de-gas tank, I hear) about an inch or two from the top full of coolant? I realized it has a weird shape, and in ATTEMPTING to eye it up to the "Full - Check Hot" line (I did, after a two hour drive,) line and simply making it very full.. Is that fine?

I put on a brand new OEM 15lbs pressure cap today. It is a.. Let me look, it is an ACDelco RC95 cap, and the car no longer has "sloshing" sounds coming from the dash.. it always had a Stant Lev-R Vent cap, and no driveability issues, but, it seems smoother with the proper cap. So, in the event it needs to suck down some coolant and exchange all the air out.. hopefully the proper cap is helping it do that. BUT, if all the air is already displaced (heat does get hot, was nice and toasty in the cabin today cruising with 28-31 degree air temp today, seemed appropriately hot, not the hottest heat I ever felt but hot enough, if that makes sense) is it OK if that one is a little bit full? Will it puke some out when summer comes and it is 100 degrees outside and the AC is on every trip or no?

Other than that, I seem to be getting 20-22MPG, cruising at an average of 70-75MPH on highways, is that about right?

And, what conditions should I test out my 4WD (4 Hi.) Pouring torrential rain? Snow ONLY? And, if I do.. do I press 2 HI after that, THEN turn the truck off? I don't want to get my truck stuck in 4WD, which I have heard of happening, and would like to test it at least ONCE, even if just for 5 minutes, in the next heavy rain or snowstorm, as I heard you are never supposed to use it on any kind of dry traction environment.. Is heavy rain enough? Don't use in light rain.. ??? (Don't use at all? Will it "break" if you DONT use it? should you use it once a year?)

Also, do you all agree with this diagnosos of getting ABS light to go off?

 

I used a sharpie to extend the the Add and Fill lines around the side of the overflow tank so that I can look down into it and with my finger on the line, I can see if the liquid level is up to the shadow of my finger or not. When I had occasion to take off the tank for some reason I could see that way in the back there was still a lot of the brown sludge that formed when the wrong coolant was put into the system. It took quite a bit of effort to get it all out.

As for testing your 4wd, on dry pavement going slowly in a tight circle you will hear and maybe even see the front tires skipping while making a sharp turn. Best to do this in an abandoned parking lot. But to explore how the 4wd can help you out, get to some gravel or snow where the tires can slip if you are going to go for any distance. Wet pavement will not let the tires slip.

And finally, it is not unheard of for radiator caps to fail. I had one fail recently. It was losing coolant from the main seal. I then had no or little suction to pull back coolant.