Used Car And New

I received these 3 questions about synthetic motor oil change intervals today from a friendly subscriber. They are great questions because if you are not careful you can end up spending way too much money paying the greedy oil companies or at the other end of the spectrum you can end up with engine damage, reduced performance, burning oil etc…

Let’s stop the suspense and get to the questions…

#1 I know the 3,000 mile oil change interval is a myth for convetional motor oil but how about synthetic motor oil?

#2 When is the right time to change my oil if I have not met the mileage limit of the oil yet?

#3 Will an initial higher TBN number be beneficial if I’m using oil analysis?

Those questions are great and I hope my answers are some help, so here they are:

Back in 1997, when Castrol managed to get the courts to allow group III basestocks to labeled ’synthetic’, the line between synthetic motor oil and conventional motor oil became very ‘gray’. So as far as the 3 month 3000 mile myth goes I can’t make a clear distinction between conventional oil and synthetic oil. to make a clear distinction between the two.~To make a clear distinction between the two has since become quite difficult and the 3,000 mile/3 month ‘myth’ can’t be legitimately negated.} I will say that in general, the 3K myth is even more of a farce where synthetic motor oil is considered. A quality synthetic oil with a decent additive package will outlast a traditional conventional oil any day of the week.

Questions #2 and #3 share the common issue of TBN. It is important that the detergents and alkalinity (related to TBN) of the oil are provided for an anticipated duration of the oil in the engine. Additive packages vary depending on the motor oil and their recommended drain intervals. To ensure that your engine’s environment doesn’t become corrosive or acidic, the TBN would be higher.

Very short drives are hard on oil (like down to the grocery store). Typical stop and go driving in the city is considered severe conditions with respect to oil change intervals. have the time to let their engine heat up properly and then unburnt fuel and moisture end up diluting the oil and breaking it down.~When you don’t allow the engine to properly heat up, as most city people do when they’re in a rush, they don’t let the oil bake out and then unburnt fuel and moisture dilute the oil and therefore break it down.}

For that reason it is best to start up and run down the highway for greater than say 15 minutes to really allow the engine to cook the oil “dry”.

Depending on your driving habits, your oil will deplete itself if it isn’t designed for longevity with a higher TBN and more detergents, etc.

The complexity of additive packages in oils is mind boggling. Additives are attached with costs, and each additive must balance with other additives. In order to get it right, the proper testing must be done.

The best way to evaluate the longevity of a motor oil is run it in your engine and perform periodic oil analysis. As long as the oil additives in your oil are appropriately balanced then the TBN should stay elevated tonger and keep your engine safer to last through extended drain intervals.  You can find the best motor oil review for all the different oils using a google search.

I’m inclined to stick with either Mobil 1 Synthetic oil and AMSOIL Synthetic Oil. For the past 7 years I’ve used AMSOIL at oil change intervals of one, yes 1, year, and on the same 2 vehicles without a single gripe or complaint from either of my engines.

The improvement in gas mileage or horsepower is slight and may be very hard to detect. The difference you might feel when you had a brake caliper dragging or low tire pressure is equivalent to what you might feel with that difference in horsepower or gas mileage. When I hear people say that they felt a difference when they switched their oil or used an additive I have to chuckle inside my head.