Make what you will of this, I put a set of NGKs in my M 50k ago and still going strong
Spark Plugs There is no reason to deviate from the factory-recommended Bosch or NGK spark plug specification, changed at 30,000-to-60,000-mile intervals, depending upon the car and severity of service. Basically, any BMW produced after 1993 can easily run 60,000 miles on a set of spark plugs.
The factory also has part numbers and applications for “100,000-mile spark plugs.” These are good too, and are capable of 100,000 miles of service assuming no other problems, which might cause them to foul during that time. However, in engines with spark plugs recessed into the middle of the cylinder head, oil can leak into the spark plug recesses past the valve cover gaskets. This is a hidden leak if the plugs are left in service for an extended period of time, because no one looks in there until they’re changing the plugs or chasing a problem. An oil leak in the spark plug recesses, left to fester, can cause ignition coil failure and even ECU failure. So, even if you want to leave the plugs in service, you should at least check the spark plug recesses for signs of oil leakage at least every 60,000 miles. And at the point you’re in there, you might as well replace the plugs. This is the issue with 100,000-mile plugs.
Moreover, while you may not have any problems running spark plugs for 100,000 miles in some BMWs, this does not mean the plugs will not be worn, or that that wear is not affecting engine performance. In other words, for optimum engine performance, most BMWs want spark plugs about every 60,000 miles.
Note that older M cars except the US specification S50/S52 powered E36 variants want plugs about every 15,000 miles.
Stay away from platinum plugs in BMWs. These don’t last as long as the regular Bosch copper or silver plugs and NGK plus, and have been known to fail in other ways. The regular old Bosch Platinum single electrode plug is, however, a very good choice for cars OTHER THAN BMWs.
Bought my 1998 Z3 2.8 a few months ago mileage reading 45.000
it was last serviced in 2019 i think the chap I bought it from said he changed the spark plugs using genuine BMW ones then, its only done about 3.000 miles since then
I am thinking good idea to do service and oil change as it will have degraded over the 3 years
but given the suggested 30.000 to 60.000 mile interval will spark plugs be ok, no sign of any problems, and wouldn't think plugs would degrade
thanks for the info, will just do oil change for the moment think that's the urgent one
underside , brakes etc were checked at same time a mate of mine did the MOT
have lost use of friends car lift at the moment so will get it done by reliable local garage
making sure they use the correct oil even if I have to get it,
If leaving them in for the full service interval, it might be an idea to loosen and retighten regularly. Prevents them seizing and snapping when you try and take them out.
Usually have mine changed every 3 years regardless, to prevent problems. Interval is 40k btw on mine
I do mine every 2-3 years regardless it’s a job I can do easily I get the placebo effect of the car running so much better and I get to use this tool out of my tool box .So all in all the price of spark plugs is very cheap...I’m getting some tomorrow can’t wait