Posted by John G. from NC on April 09, 01 at 08:14:12:
Hey, everyone. Starting to heat up here in central NC.
Got my first oil analysis back from Blackstone Labs (http://www.blackstone-labs.com/), and wasn't entirely excited about the results! I've got a '99 K2500/7.4L with 46,000 miles. Everything was reasonable except for iron content, which was at 69 ppm rather than the ~25 ppm reported as a universal average for my engine. I ran 3,400 miles on Mobil dino oil 5W-30.
YIKES! Anything I'm doing wrong to warrant that iron content? Ideas?
Blackstone commented that iron is usually from cylinders, and that I should switch to 10W-30 for my next run and keep the interval at 3,000. Of course, I had already replaced the oil with Pennzoil 5W-30.
What's all of your thinking on this? Now, before we get into the big dino/synthetic debate, which we all know is highly subject to personal philosophies, you should know that I do not tow at all, and am of the opinion that good quality dino oil and a high quality filter (planning on sticking with AC Delco) is probably just fine for my standards. I was planning to stretch oil change interval to 5,000 or 6,000 miles, but obviously I won't do that just yet.
According to my manual, I can run 10W-30 at temps above zero F, which is the case 99% of the time where I live. I know some people say you can get better motor protection but slight loss of MPG with 10W-30 rather than 5W-30, which GM has been recommending for some time in their new vehicles. I had heard that they started recommending 5W-30 some years back as a cheap way to get a tiny increase in MPG across the fleet, in order to help their CAFE numbers (Corp Avg Fuel Economy).
I've been running 5W-30 since I got the truck, but am thinking that an overall switch to 10W-30 might be in order like Blackstone says, assuming that the 10W-30 would give my a little better protection due to increased viscosity.
Opinions? (donning Nomex suit with riot shield) :-)
Thanks all for a great board,
John G. from NC