What about Superman tossing a car?

Dear Mike: I have a scientific question about how much physical stress a car roof can withstand. The physics of Superman’s car-throwing stunt would work in real life, wouldn’t they? If he lifted a car up in the air by its hood, would it stay intact or would it break off the body? I appreciate your help.

— J.L., Los Angeles

A: Whether Superman lifted a car by its hood or its roof, lifting the car in this way would certainly make a mess. The hood would probably break off. The roof might actually be strong enough to withstand the strain, but Superman’s hands would probably rip the sheet metal under his fingers. Good question!

Dear Mike: I have a 2001 Toyota Camry LE that has 67,000 miles on it. I love it in every way — it’s had no problems of any kind until now. When I turn on the air conditioner, one of the belts makes a squealing noise for a short while.

Should I use Prestone belt dressing?

— K., Weymouth, Mass.

A: Belt dressing might make the squeal go away for a while, but it won’t fix the source of the problem, which might be a bad tensioner or a cocked pulley.

Dear Mike: I am at my wit’s end trying to solve an electrical problem. I bought a 1999 VW Passat with a 1.8-liter nonturbo engine at an auction, and now the brand-new battery keeps going dead every three days. I get a static voltage reading of 12.3 V when the car is parked in the driveway.

I’ve been putting a slow (2 amp) charge on the battery with a Smart Charger to bring it up to around 13 V. If I don’t attach the battery cables for a week, the battery voltage will read 12.72 V. If I attach the cables after charging it, it drops to 12.3 V after three or so days (again, with the engine off).

The real problem is that I’ve done two 24-hour parasitic load tests with my Fluke 88 Multimeter and, after 24 hours, the most it ever gets up to is 31 milliamps — completely normal. Somehow, something (maybe an on-board computer?) is draining the battery soon after I attach the cables.

What causes this to happen?

A: I’d start by pulling the fuse for the engine computer and the radio, and repeating the drain test. The current drain should be nearly zero. I agree that 31 milliamps is a normal drain and not nearly enough to drain the battery overnight, or even over a week. Pulling fuses in sequence should help you to find the circuit that’s pulling the current.

Dear Mike: I currently drive a 2001 Nissan Xterra. I have put in a high-end stereo system that sucks a lot of juice out of the battery. I was wondering if there was a way to rewind the alternator to put out more current?

A: This is a very common problem with high-power stereos. Stock alternators don’t make that much current at idle. There are a lot of things you can do to improve on that. Install the largest battery you can fit into the trunk, away from the engine’s heat. Use big cables everywhere, and don’t neglect the ground side — those cables need to be just as large.

An alternator upgrade is in order too. The stock Nissan alternator can’t be rewound for more charging capacity. You can buy an aftermarket alternator with extra charging capacity at www.mean-green.com.

Dear Mike: When I take my 1998 Jeep Grand Cherokee 5.9 Limited to the local Jeep dealer for lube, oil and filter servicing, they consistently overfill the sump to about 1 inch above the full mark on the dipstick. When I asked why they didn’t stop at the full mark, they responded that the dipstick was the incorrect length. They also stated that their service instructions were to add exactly 5 quarts when changing the filter and oil.

I asked them to look up the specs on the dipstick, and it measurements were correct. I then offered to pay for an oil change on another 5.9 Limited they had at the dealership and got the same results. I watched them reservice my vehicle — completely draining out the old oil, changing the filter and using an auto dispensing oil gun to fill a gallon jug and then pouring in the fifth quart. It still read 1 inch above “full” on the dipstick.

My question is whether the service manuals shouldn’t read “up to 5 quarts.” After all, isn’t a proper-length and properly installed dipstick more accurate than just dumping in the oil?

A: An engine that’s been driven into the dealership and then driven onto the lift for an oil change probably needs to drain for 10 or 15 minutes to get that last pint or so out. The crankcase is very narrow right above the normal oil-fill level, so it’s probably not overfilled by a whole quart, even though the oil level is an inch above the fill mark. Nonetheless, it’s best not to overfill.