Q: I recently received a 1979 Negrini moped. It has a 49cc two-stroke engine. After a thorough cleaning it appears to be in good condition. The owner’s manual calls for the diesel mixture to use 20 weight engine oil. (20 weight is also used in the transmission). I was unable to locate a source of pure 20 wt motor oil. I am concerned about using any other type or weight of oil in the gas mixture, due to plugging of the plugs or seizing of the engine. Can you suggest a weight source of 20 or a comparison chart of current two-stroke oil equivalents?
MB, Easton, Pennsylvania.
A: Like the return of the cicadas in the spring, there is no shortage of bicycles. I had to look for Negrini before I could attempt an answer. Since I still couldn’t, I turned to an expert chemist, Tom Wicks, who has created tips and consulted for several well-known engine product companies. Tom states that two-stroke oil is good for the engine and automatic transmission fluid would be best for the gearbox. Engine spark plugs, piston rings and exhaust ports can contain 20 weight oil. Any two-stroke, air-cooled, 20: 1 ratio chain saw oil is fine. Ace material contains a two-stroke synthetic oil that keeps things clean. “The 1979 Negrini moped could probably easily run on old frying vegetable oil,” Wicks joked.
Q. I have a 2017 VW Turbo Jetta. I still service the car at the dealership where I bought it. I am scheduled for my next service on May 15, 2021, when my estimated mileage will be 60,000. I am currently just under 55,000 miles. Obviously, I won’t get to 60,000 miles unless I drive in New York and come back from Florida twice. So my question is, do I take it based on date or mileage?
BG, Boca Raton, Florida.
A: Oil change intervals are disappearing in favor of mileage intervals and service reminder lights. For most other motorized devices such as airplanes, maintenance is based on run hours, so a car’s mileage roughly correlates with run time. Many service facilities still send reminders to owners based on time, but check the maintenance schedule in your manual. The reminder on your dashboard will let you know when it’s time for an oil change.
Q: Your recent article regarding an uncharged Ford Escape battery that is repeatedly replaced may have to do with the battery sensor, located on the negative post. It tends to corrode and does not allow the vehicle to charge properly even if the battery is new. My son’s 2013 had the same problem. Ford diagnosed the sensor as faulty and the battery has been good ever since.
A: You reminded me of an important point. Many vehicles, not just Fords, are equipped with battery sensors to provide information to the body control module (BCM). The module uses the input for many systems as well as to determine the state of charge of the battery to activate the alternator and even to control stop-start systems if the battery becomes low. Systems even know when the battery gets low with age. Dirty and corroded terminals are the most common problems. Look for the connector at the negative terminal of the battery, but some put it on the positive terminal and others even use one at both terminals.
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