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November 03, 2009


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Anyone have any thoughts on Nitrogen in the tires? Btw, yes I know that air is 70% nitrogen. Seems like a good way to give dealers free money?

And remember that you cannot get a jump-start from a did not even think about that until it was an issue a year ago. My Chevy Aveo needed a jump, I was on my way to work, my husband had just bought his used 2007 Prius, and it hit us that it would be absolutely useless. :)

We were actually thankful that we rent out our 3rd bedroom since our roommate was nice enough to help out. It was a pretty funny epiphany moment...

If you'd rather not re-inflate tires often for seasonal changes (gain/lose approx 1 lb for every 10'F) then pay the $$ for nitrogen, you'd be better investing in a good pressure gauge, keeping the tires at/to w/in 2 lbs of the CAR Mfgr's recommendation for full load pressures, and try to rotate those tires (inspecting brakes, suspension, CV boots at this time) every other oil change...My car has never been to a dealer, I do the work at home, that includes: coolant, transmission, differential, brake and clutch fluid changes (check owners manual, often folks over change the oil and neglect the other fluids! - EVERYTHING is in the owners manual, read it 2X a year!) Realize spark plugs really aren't best left in 100K miles, often they literally melt to the heads, they are relatively cheap, replace 'em at 1/2 intervals and do the plug wires when the manual recommends plug changes for good mileage, dependability. Try to often (at least 2x a year) thoroughly wash and rinse the UNDERSIDE of your car, that pays in maintenance, repairs and preventive care! again, RE-ERAD THE OWNERS MANUAL!!!

Gotta disagree with the "reality" aspect of the premium vs. regular grade fuel. Again, that's something that you should follow per your owner's manual. Most cars don't need premium grade fuel, and you're just wasting money if you pump that into your car. However, if your manufacturer has designed the engine for higher octane fuels, you should put them in or you could experience downgraded performance, engine knocking, and stalling.

I can agree with the other statements, but I'm surprised CR would put out such a blanket statement about the fuel issue. I'm sure a lot of sports and luxury car makers wouldn't agree with it either.

Prius jump starting: Looks like you can...

Oil changes are a farce... 3000 miles died a long time ago. Conventional oil can be changed every 5000-7500 miles and fully synthetic 10,000-15,000. We had just bought a new MINI, and I was talking to the tech about this. They told me that it is a big scam, I mean $50 plus my time every couple months... ouch. My MINI has followed the computer's service requirements to the tee, and our oil changes (fully synthetic) have been anywhere between 10,000 and 21,000 miles (I kid you not). Of course with MINI (or BMW's) it's all free anyway:)

It looks like it might be possible but you run the risk of either not having enough juice to actually start or "popping the master fuse between the 12V battery and the inverter in the Prius"...I don't know what a master fuse costs, but the battery costs thousands of dollars. Good to know in an emergency, but a little too risky for me on a normal day. Thanks though!!!

Thanks Jeffinwest,
You sparked another qx for me re the nitrogen. Do tires filled with nitrogen use the same kind of tire gauge? As you can tell by my qx's there's no way I could self service my car, ;->

Thanks for offering practical tips on cars which everyone can always use in order to save a ton of money. It's good and it's very helpful to personally know a great mechanic when one needs him.

I agree that one can afford to overlook on certain car maintenance such as fluid change, but not on all like tire pressure.

One more thing on oil changes: If you use synthetic oil, you can usually get away with waiting until 10,000 miles. Most times, this can be cheaper than changing the with regular oil.

Speaking of premium gas, I just inherited a salvage Acura car recently. The cars manual says to use premium gas but since it is a salvaged and repaired vehicle, is this still recommended? Any suggestions?

Hi… maintenance is a must for everyone of us, because this
will extend the life of the car and help save costs in many
categories, such as spare parts, engine performance, etc.

If the cars computer can change the timing, often regular runs fine, my Mazda Miata's owners manual explains this CLEARLY, about a 6-10 hp loss but, $$ saved. Modern cars (OBDII computer systems) that ask for premium usually run fine on mid-grade 89~ octane or 87~ regular, w/ light loads, cruising, level roads, that ALSO mean a lower octane can be used, high reving, towing, hard acceleration, hills often make a car like higher octane. Brand DOES make a differnce as far as proper detergents in fuel too but, often the extra cost of top shelf fuels (Chevron, Shell, 76, Texaco, et all) can be offset w/ a servicing of the fuel system every 50K~ miles or so. Ther ARE differences w/ oil FILTERS, I'd advise using a synthetic medium filter (Pureolator Pure One, Mobil One, etc.,) w/ true synthetic oils, otherwise, change the cheap ones every 5000-7500 miles. Botiue oils Amzoil, Royal Purple are often overpriced for teh same wear/protection factors as Mobil One, Penzoil Platinum, etc.,, skip the so called blends, just advertising makes them sell. Cars that get low mileage use as well as a lot of driven miles benefit most from synthetics. Like I said above, don't neglect other fluids such: coolant, tranny, differential and filters: oil, air, cabin and hoses, clamps, belts plugs and wires, typically all need replaing at 90-120K miles...just going to Jiffy Lube and ignoring the rest is NOT maintenance!

I'm just some guy on the internet, not a mechanic, but I'm really skeptical that modern engines which were designed to run on premium gas actually need it.
They will suffer some performance loss burning lower octane gas, but I believe that all but the most aggressively tuned high performance engines can sufficiently adjust their timing to prevent knocking and pinging. As long as your not pushing you car too hard, I don't think regular gas would cause any problem.

Tire Pressure
I always kept my tire pressure a couple PSI above the pressure written in the door jam, but they were always flat and the tread wear showed they were flat. I later found that the recommended pressure is 80% of the max PSI of the tire (some people even go up to 90%.) The pressure listed in the door jam should be 80% of the max pressure for the STOCK tires, but if you changed tires the recommended pressure may have changed.

@Eric: Yes, Acuras are designed to operate at higher compression so the higher octane is recommended. Some have tried both regular and premium gas meticulously recording their fuel efficiency, and found that they get better fuel efficiency with premium fuel, completely offsetting the higher cost. So regular gas may not be saving you anything (and how much harm it will do is often debated.)

The reason that some engines require premium fuel is that in order to gain performance they operate at a much higher compression ratio. At high compression ratios regular gas will cause pinging, knocking, and could in the long run cause damage to engine bearings. If you can't afford premium when the manufacturer states that it is required then you should buy a car with a lower performance engine.

Diesel engines operate at far higher compression ratios. The engines are built much stronger to withstand the higher forces but you can still hear a Diesel automobile coming from a hundred yards away.

Our newer Mercedes requires both premium gas and synthetic oil. Using non synthetic oil can eventually clog up piston rings and lead to expensive repairs, as well as voiding warranties. The synthetic oil requires changing every 10,000 miles under normal driving conditions. If the manufacturer supplies their own brand of oil filters I would also suggest that they be used. If all you need is a change of oil and filter you can save money by going to places that specialize in oil changing and avoid being ripped off by your dealer. They will credit you for bringing your own filter.

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