I have a 99 Dakota CC pickup with the 3.9L engine. The VECI label says to use RC14LS4 spark plugs. I have been told that Autolite 3923s are the best for my truck. I live in southern Ontario and can't find Autolite plugs at any of the parts places here - Can. Tire, UAP, etc. Any suggestions where to look or if these are even different?

 

Being from the "old school" I would use whatever the book say's for this engine.

 

Follow the VECI label---it's there for a reason.

No need to use anything but the OEM plug in this vehicle. I agree with Darrell.

 

I've run into situations where the spark plug mentioned on the VECI label. 1988 Chev Celebrity Eurosprt wagon was one....GM discontinued using the original plug, and a different one was to be used!

 

Correct. Such is the case with my 84 Oldsmobile 307 V8. R46SX was the original, now it's R46SZ which is for a different gap.

However, the heat range is the same and so is the plug design. Leave that to an engineer to determine!

 

Here's my 2 cents I post on a number of boards on the web and I constantly see people using the wrong plugs and having problems. This is especially true of the newer engines. I always tell everyone to use what the manufacturer of the vehicle calls for. Stay away from those Gold Plated Nuclear Powered plugs that the parts guy says will last 2 Lifetimes!

 

Correct. A manufacturer supersession is one thing. If you go to Sears' website and look up parts for my 1965 snowblower, you'll find that most available parts are superseded to a different number. But that is the MANUFACTURER stating that the change is valid. Their engineers have tested the new part versus the old and advised that the change is OK. Or the part is improved over the original.

A "customer" supersession is something else. You're not basing it on anything but your experience .

In my case, GM is stating that R46SZ will work for R46SX.