Your cap may need to be tweaked

Dear Bob: I have a 2002 Ford 150 Super Crew 4X4. My gas mileage used to be 16.5 mpg to 17 mpg with a Tano cover. Recently I installed a cab-high cap, and my mileage decreased to 12 mpg to 12.5 mpg.

Is there something I can install on my cap, such as an air foil? Or do you have any other suggestions?

Thanks,

— G.S., Mechanicsburg, Pa.

A: Your in-town mileage should not have been affected so much by the addition of the cap. It’s only when you get past 45 mph that wind resistance can play a major role in reducing your fuel-efficiency numbers.

You might check to see if anything else has changed to contribute to this loss.

Assuming that the new cap is what caused your drop in gas mileage — and it surely is at least a contributing factor — it’s the cap that must be tweaked to try to get back some of the mpgs it stole in the first place.

Some of the loss can be attributed to the weight of the cap, though, and there is nothing that can be done about that.

The only thing I can suggest is adding some type of spoiler to help reduce the wind drag caused by the cap.

You might want to check some high-performance truck and car centers to see if they have a spoiler that will fit your cap. While I doubt that a spoiler would do much good for your in-town fuel economy, it might be helpful at highway speeds.

Dear Bob: After reading your column about the spare without air, I had to write to you about the poem I made up. Hope you like it:

“You have to make sure

there’s air in your spare

That’s if you intend

to go anywhere.

I’m stating a fact

and I’m being fair,

so check that spare

If you want to get

from here to there.”

— S.S., Harrisburg, Pa.

A: Browning and Whitman

never had a spare

to fill with air.

But if they had a spare,

no doubt your words

to heart they’d bear!

With sincere apologies to Browning and Whitman … .

Dear Bob: A recent column notes that you have been mixing your own synthetic blend of motor oil for many years with good results.

It appears that your personal blend is about 25-percent pure synthetic. Is this the percentage that you recommend, or should it be higher?

Have always looked forward to your articles. Thank you.

— J.L., Newburgh, N.Y.

A: I’ve always substituted one quart of synthetic for one of standard mineral oil at oil-change time. This works out to an overall blend that’s 20-percent or 25-percent synthetic, depending on whether it’s a four-quart or five-quart crankcase. This has worked great for me.

There would be no harm, of course, in making it a higher percentage by adding more synthetic to the mix. But the cost would also be higher, negating the whole reason for mixing oils in the first place.

As I noted in that column, manufacturers of synthetic-blend oils are not required to list how much synthetic is in any given blend, so buying them is a crap shoot. Using my method, you know exactly what percentage of synthetic is in your home blend.

And don’t worry, if you have your oil changed at a shop, they will be more than happy to oblige you by adding to the mix either their own quart of synthetic or the quart you happen to have with you.

AMERICAN DRIVERS FIGHT BACK

Here’s a tip that will help you get better gas mileage while fighting terrorism and cutting our nation’s dependence on Mideastern oil:

Don’t tailgate! A great deal of gasoline is wasted by driving too close to the vehicle ahead. When you tailgate, you are forced to constantly brake and accelerate, brake and accelerate. In other words, you’re letting the car in front of you dictate how you drive — and that’s both foolish economy and unsafe driving.

Keep a safe, reasonable distance behind the car in front, and you won’t have to play the fuel-wasting slow-and-go game. It’s murder on gas mileage. Keep smooth, even pressure on the accelerator and pace yourself so that you are not continually slowing and stopping in cadence with the car in front.

You need an air cushion between the two cars. Maintaining a buffer zone of 2 seconds or so — when traffic allows, of course — gives you time enough to react to whatever traffic situations may develop and allows you to make the best use of the momentum your car has built up, momentum that you’ve already paid for in the form of gasoline burned.