i have just gotton a inline 6 and was wondering what oil ya'll would suggest to use, i put about 3 to 4 thousand miles on my trucks a month. thanxs

 

The emissions sticker under the hood on my '94 says "10-30".

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'94 E-150 Conversion Van 4.9 / C-6 -- '89 Mustang LX 5.0

 

in my 78 inline 6 i use that quaker state semi sythendic stuff for 4x4's and hard working engines. but i used to use valvoline 10 30 or quaker state 10 30 before the sytendics came out

 

If it doesn't have leaks, I'd suggest a full sythetic. Manufacturer's recommended fluids are minimum requirements, not set-in-stone guidelines. If you're using it that much I take it you probably want to reduce wear as much as possible (and keep it running cooler, and save some gas, and etc. etc.), so a full synthetic is the best choice.

Worst choice is a dinosaur oil that is too thin or thick for the normal driving conditions you face, cheap dino oils, and (per a lot of posts here, plus 20-some years of hearing complaints) Quaker State. It amazes me that I've been hearing coninual complaints for twenty years that Quaker State gums up engines - do some searches in the Oil and Lubrication section and you'll find rather current posts from people who took their engines apart to only find sludge. In this day and age a lubricant should not gum up, nor should it not conform to the initial standards (viscosity, shear strength, etc.) it was made to after only 3000 or 4000 miles.

I think if I were forced to do use dino oil, I'd just stay with a quality 10W-30, or move to a 10W-40 or 15W-40 in hotter climates (or in leaky situations).