James D. Halderman is an ASE-certified master technician, a member of the Society of Automotive Engineers and the author of 12 textbooks. Submit your automotive care questions to Halderman via e-mail at jhalderman2@juno.com, or write him in care of: Wheels, Marketing Publications Department, Dayton Daily News, 1611 S. Main St., Dayton OH 45409.
Wheels: GDC writes: “I got into a bit of an argument with a guy at a parts store yesterday and have heard this same thing from guys at others, too. The disagreement centered on changing from regular mineral oil to synthetic oil. This guy yesterday told me that once I changed over to synthetic oil I could never go back. I told him he was wrong and full of misinformation. Here is what I told him:
• Mixing regular oils with synthetic would do the same thing in that a percentage would be synthetic and a percentage would be regular oil.
• This is how they are able to sell synthetic blend oils — they can be mixed together in any amount.
• If you have regular oil in your engine and decide to add a quart of synthetic oil, it is just fine and vice versa. Therefore, going back and forth between regular and synthetic makes no difference.
• The exception to this is when you are breaking in a brand-new car/engine; you cannot use synthetic oil, as the engine requires regular oil to break in the engine properly. I think this would make a great question.”
Halderman: Here are some general recommendations:
• While some engines come from the factory with synthetic such as the Chevrolet Corvette (Mobil 1), most experts recommend that the engine first use regular engine oil until after the first or second oil change.
• Always use the recommended viscosity and API rating. Some synthetic brands are not API-approved and therefore they are not recommended by the vehicle manufacturer. Look for the API doughnut on the back of the bottle and do not think that it meets the API standard when the container says “meets the API standard for SL” or similar language.
• Always follow the recommended oil change intervals. Some brands of oil, both synthetic and regular, recommend that the oil change interval can be extended. Always follow the vehicle manufacturer’s recommended oil change interval.
• A blend of synthetic and regular oil can be used, but as there are no standards that state how much synthetic is included in the blend, I recommend that a good quality conventional oil or full synthetic oil be used.
• You can switch between regular oil and synthetic at any time, but the advantages of having used synthetic will be lost, so consider continued use of synthetic.
James D. Halderman is an ASE-certified master technician, a member of the Society of Automotive Engineers and the author of 12 textbooks. Submit your automotive care questions to Halderman via e-mail at jhalderman2@juno.com, or write him in care of: Wheels, Marketing Publications Department, Dayton Daily News, 1611 S. Main St., Dayton OH 45409.
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