[wi.st.rod]

We own a 2018 430i xDrive Convertible (purchased it as a CPO in December 2020 with 21,000 miles on it). It is a seasonal car for us; we put about 3,000 miles on it, and today it has a total of 30,000 miles. It is due for an annual oil change, and we received a BMW notice indicating that the spark plugs are due for replacement as well.

I realize the service manual indicates spark plug replacement at the 6th oil change (approx. 60,000 miles), which is where we are at, but I have a hard time believing the plugs ought to be replaced at this time, with only 30,000 miles on the vehicle. While most of our use is short trips (around town) we just completed a 650 miles trip; the vehicle runs fine (no rough idling, no misfires, no reduced acceleration, etc.).

Should I just bite the bullet and have them replaced, following BMW's recommendations, or is it a waste of time and money doing so? Also, any idea what dealers are charging these days to install 4 new spark plugs?

[Billfitz]

It's probably based on time, certainly not mileage. You can be sure BMW will charge twice what an Indy does, and ten times the cost to DIY.

[wi.st.rod]

Thanks.

It is definitely based upon time, as spark plug changes are recommended at 60,000 miles or at the 6th oil change. Oil changes are based on time or mileage, every 10,000 miles or once a year; so if 10,000 miles a year aren't logged, the 6th oil change would occur when the vehicle is 6 years old (ours just turned 6 years old), therefore triggering the spark plug replacement timing.

I understand why replacing the spark plugs is being recommended, it's because the vehicle is now 6 years old. I just never realized that spark plug life was impacted by age, as opposed to miles driven, and that's why I'm asking if it's beneficial to follow the BMW recommendation and change them on a 6-year old car with 30,000 miles.

[Billfitz]

I wouldn't.

[AspektUSA]

You can push it to 40k miles, but I'd consider pulling it.

Don't want things like it getting seized.

Preventative maintenance is a beautiful thing.


I changed my 6 at 50k mi and felt it was right.

[thejeremyman9]

Reasons to shorten the interval can include:

- short trips
- tuned
- harsh environment (they can rust)
- car sits a lot
- oil leak on VC seals

Up to you how preventative you want to be... if you feel like getting the most out of them you can always look at the front one and check as it would only take a few mins