Should I change to synthetic motor oil in 1994 Celica? | Car Doctor
Q: I have a 1994 Toyota Celica and have always used conventional oil. Should/can I change to synthetic? Can I mix the two?
A: Although there are synthetic blends, it is never a great idea to be a “driveway engineer” and mix oil. On a rare occasion, there can be some compatibility issues with the additives in various brands and types of oil. Considering the age of your car, I would stick with the Toyota recommended oil, which is 10W-30 SG conventional oil.
Q: Any idea why no one has filed a lawsuit against the auto industry for their defective headlight lens covers? I consider cloudy lenses a dangerous situation. I feel the auto industry should replace these lenses at no cost to the consumer.
A: You are correct that proper lighting is important. In fact, AAA did some testing and found that badly discolored headlights can limit light output by up to 90%. The clear plastic lenses are subject to discoloration from abrasion, ultraviolet light and improper bulb use.
Lenses can also be damaged during servicing if a fender cover is over the lens and the headlights are on.
The lenses can, with a little care, last a long time but are considered a part that can wear out. Lenses can be restored/polished, and there are also good-quality, cost-effective aftermarket headlight assemblies. These aftermarket lights will not just allow better night driving performance but will improve the look of the vehicle.
Q: I have two plug-in hybrids. In these cars, the electric motor is primary and the fuel motor comes in as a booster to provide longer range. Because of that, for most "around town" driving, the fuel motor does not run. If it does run, it's only for a short time.
However, on a long trip, the fuel motor does all the work — after the charge runs down — with the electric motor providing a boost when the car needs extra acceleration.
The manufacturer recommends synthetic oil, and that is all I have ever used in these engines. Should I make sure the oil is pure synthetic, given the unusual duty cycle of these powertrains?
A: Synthetic oil and hybrids, or plug-in hybrids, were made for each other. I would just use the oil weight and grade recommended by the manufacturer. I wouldn’t be concerned about brand, as long as it meets the specifications. As an example, the Prius Prime uses 0W-16 API SN/RC oil. This is a fully synthetic oil and the only oil that should be used in that engine/car.
Q: Can you comment on the advisability of installing an AGM (advanced glass mat) battery in a vehicle that was originally equipped with a conventional lead-acid battery? Perhaps there are differences in the vehicle charging system or electronic controls of the system that would lead to incompatibility?
A: Substituting an AGM battery for a lead-acid battery can get a little controversial.
At AAA, we believe that you should stay with the same type and design of battery that your vehicle came with. The reasoning is the charging system was designed for a certain design battery, and that is the battery that should be used in the car.
Some battery retailers will show good, better, and best batteries and list the AGM replacement as the “best” battery.
Until vehicle manufacturers approve upfitting to a different battery, I would use AGM batteries in vehicles that came with AGM batteries and lead-acid batteries in vehicles that came with lead-acid batteries.
Q: I own a 2015 Hyundai with 78,000 miles on it. The engine burns oil, but not all the time. I can go 500 miles on the highway and not use a drop. Other times I can drive 300 miles around town and use a quart.
When I went to the dealer because of the 10 year/100,000-mile warranty, they told me they didn’t find any issues. What should I do?
A: Some Hyundai engines had problems with the piston rings sticking and causing oil consumption. The repairs range from an engine flush to an engine replacement.
At this point, I would ask the dealer to perform an oil consumption test.
Drive normally and have the dealer check the oil as required. If the engine is using more than a quart of oil in 750 miles, the repairs should be covered under warranty.
John Paul is the AAA Northeast Car Doctor. He has more than 40 years of experience in the automobile industry and is an ASE-Certified Master Technician. Write to John Paul, The Car Doctor, at 110 Royal Little Drive, Providence, RI 02904. Or email jpaul@aaanortheast.com and put “Car Doctor” in the subject field. Follow him on Twitter @johnfpaul or on Facebook.
This article originally appeared on The Providence Journal: Car Doctor: Should I change to synthetic motor oil?
