6.5L diesel engine

**idun** · 06-11-2008, 02:08 PM

Hi there, I'm looking to buy a Suburban in the near future... I found a nice one... 1999 with the 6.5L diesel engine. I was just wondering what king of fuel consumption can I expect from this truck when I drive it on the highway, without towing anything ?

**vncj96** · 06-13-2008, 11:59 AM

Not sure about mileage but not a great engine.

**John W** · 06-13-2008, 12:31 PM

I would leave the 6.5 right where it is.

**Pete95Sierra** · 06-13-2008, 01:04 PM

the 6.5 diesel were not a good engine as they said and the fuel mileage is still to gonna be very good.

**tbplus10** · 06-13-2008, 02:18 PM

The 6.5 isnt as bad as everyone makes it out to be.
When properly tuned with good maintenance it can go over 250K before needing a rebuild. Mileage in the neighborhood of low 20's is possible unloaded, loaded mileage runs in the high teens. The 6.5 isnt a torque beast like the newer Diesel engines but it can hold its own against similar sized gasoline engines while towing and still return better MPG and longer time between rebuilds.

With a few tweaks it can do much better.
The Fuel control can be adjusted to improve HP, but at a loss to MPG, and I wouldnt attempt this unless I installed a Pyrometer first, tail pipe temps can get high enough to melt the manifolds if you dump to much fuel in.
Add a Gale Banks turbo kit and it'll run with a stock newer Diesel engine.
A Banks exhaust will improve mpg and performance even more.
And the addition of a Propane injector makes it run like a whole new truck giving it more power and better mpg.
I've had a couple trucks running the 6.5 and I wouldnt hesitate to buy another, I would beef it up as time and money permitted, first I'd put in a Pyrometer, then a Propane kit, Exhaust, and finally do the turbo.