Oil ChangeDear Ole Mechanic:

I just finished reading your article on synthetic oil and now I have a question.  I just brought a new Toyota that has 9,000 miles on it because it was the dealers demonstrator.  After reading your article, I called the dealership to find out what brand and type of oil had been used in the demo car.  They said that they use nothing but Castrol® synthetic 5W-30 in all of their demonstrators.  If they had put nothing but synthetic oil in it, then did it have a chance to “break in”.  How can I tell?  Should I have regular oil put in the engine to ‘break it in,’ or should I continue to use the synthetic oil?  Thanks for the help.

Ms. Confused


Dear Ms. Confused;

How can you tell if the engine is broken in?  The simple answer is to check your oil level frequently--preferably every time you get gas.  If you don't already know how to check the oil level, ask the dealer's service department to show you how to do it and how to add oil, also.

Several factors can effect the break-in time.  One of the most important factors is the quality control in the manufacture and assembly of the engine.  If it is assembled correctly with the proper tolerances, then the engine should be sufficiently broken in after 500 to 1,000 miles.  Providing that the dealership changed the oil according to the manufactures recommendation, then the first oil change would have been done at about 3,000 to 5,000 miles--plenty of miles to break in the engine.  Most manufactures do not--or at least they did not--put synthetic oil in it at the assembly plant.  Since I have been out of the manufacturing loop for several years remember, I am retired), this may have changed due to new piston ring and bearing technology.  An initial fill of a non-synthetic mineral oil is what is put in at the assembly plan,t and it will allow things to properly seat and break in.  This allows the dealer or the customer to start using synthetic oil at the first oil change.

Back to checking the oil level for a moment.  Most manufactures do not consider the consumption of one quart of oil every 1,000 miles as excessive oil consumption.  However, many of today’s engines may run as much as 5,000 miles and not use a quart of oil.  I have one vehicle that I brought new many years ago that I have never had to add oil to between oil changes.  I have another vehicle that I also brought new that will use one quart of oil every 3,000 miles.  There can be differences in engines, even if they are used in the same way by the same driver.

At this point if you have a ‘New’ vehicle or just a ‘New-to-You’ vehicle, check the oil regularly until you get comfortable with the care and feeding of your new purchase.