2018 Mazda CX-5 - Oil

The Maintenance manual says to use full synthetic oil at 7,500 mile intervals but dealer says should use full synthetic every 5,000 miles. Do i really need full synthetic or will semi-synthetic be fine? Also, do I really need to change it every 5,000? Seems like dealer just want me to come in more often and spend money.


The manual probably also has a time limit of a number of months . If it calls for full synthetic why would you even think of using something else while in your vehicle warranty period . Also your dealer might realize that you are in the severe service category. In case of warranty problems you need the dealer on your side so just do the 5000 mile changes.

This is your answer, don’t use a semi-synthetic

The user’s manual probably also includes an elapsed time between oil changes and a second mileage for driving in severe condotions. My guess is that the dealer told you 5000 assuming you drive in severe conditions, unless you had a talk with them about your daily driving habits. Then they would know whether the conditions are severe or not.

What weight oil is recommended? My son’s Mazda calls for 0w-20 which is not available in regular dino oil.

How long do you plan on keeping this vehicle (miles)? If you only keep a vehicle for 100k miles or less then 7500 mile oil change interval is probably fine. If you plan on keeping vehicle many years and a few hundred thousand miles, then I’d opt for the 5000 mile oil change.

Yes, I see absolutely nothing that is unclear about the manufacturer’s requirement of using SYNTHETIC oil.

For reasons that I cannot fathom, many (perhaps… most) people seem to focus on the odometer mileage factor for oil changes, but they seem to ignore the elapsed time factor. A driver who accumulates his/her miles slowly needs to carefully follow the elapsed time requirement, rather than the odometer mileage factor.


The maintenance guide shows 5,000 miles for severe service, 0W20 full synthetic motor oil.