Regular or Synthetic?I own an '89 Mustang GT with 53,000 miles. I purchased it a few years ago when it had 38,000 miles. The previous owner used synthetic oil from day one. I was thinking about switching back to regular motor oil. Should I make the switch or stay with synthetic?John ThompsonConway, SC
The benefits of synthetic oil are well known and I think most people who work on, know about, or are enthusiastic about cars will tell you they also believe in synthetics.
Whether or not to run synthetic oil depends on the car. For example, my '92 LX 5.0 daily driver has about 125,000 miles and burns oil (about a quart every 1,500-2,000 miles). Therefore, I choose to run regular, since the engine goes through more oil than if it were newer. I usually use one of the high-mileage oils on the market these days.
On the other side of the coin, I run Royal Purple synthetic oil in my '69 Mustang since its 351W has only about 20,000 miles on it. My rationale is that with a new engine that uses minimal oil, the synthetic is a good way to go since little or no oil will be added between changes. With an older engine, adding synthetic-which usually runs about $4-$5 a quart-between changes might be pricey. Adding regular oil between changes isn't a big deal.
Though it's more expensive than conventional oil and you have to make a judgment call as far as the car you have, I'd say stick to synthetic with your low-mileage Fox 5.0.
Belt Bypass?I have an '05 Mustang with a V-6 engine, and I've done several appearance upgrades and added a few bolt-ons to gain extra power. I don't really use the air conditioning, so I asked my local dealer service department what size belt I need to bypass the A/C compressor. They didn't know and said to try several until the right size could be found. Do you know what size I need? Will bypassing the pulley increase power and gas mileage?John SchwarzGillespie, IL
All new S197 Mustangs have A/C, so there isn't an application for non-A/C. I don't think it's worth the hassle. In my estimation, it probably only takes 2-3 hp to spin the compressor when the A/C is off. If you floor the gas pedal with it on, it shuts off automatically anyway, so no gain there. I don't think any gain would be enough to warrant going through the motions to bypass the compressor-especially in a car as new as an '05 Mustang.
It's definitely a case of trial and error to find the right belt, but it might not be possible to bypass the A/C compressor without bypassing other accessories, such as the alternator or power steering.
As far as not using the A/C in warm weather-having grown up in Illinois, I know it gets hot-common consensus among most in the automotive community is that gas mileage is actually slightly better in most cars with the windows up and the A/C on rather than with the windows down and the A/C off. The thinking is it's due to the aerodynamic drag created when the windows are down.
A ShakerI have an '03 Mustang GT with an automatic transmission that I purchased new. Over certain patches of roadway, I get a vibration from the rear of the car, which shakes for 2-3 seconds and stops. Generally, the same roadways cause the problem. I've been unable to re-create the shaking for my dealer, who says he has had no similar complaints. Any thoughts on the cause?Paul KlobasVia e-mail
It's hard to troubleshoot these kinds of problems without actually driving the car. It may be a balance issue with wheels and tire, or it could be the driveshaft. Have you had the tech ride along or drive the car on the same road where the vibration occurs?