Is it really every 30,000 miles? Torque specs are 22+ 3 ft ft lbs right? I have almost 80,000 miles and no record of this service.
Hi. Late reply here. My car is due. It is 55k miles then every 60k miles
Was wondering which spark plugs to get if not OEM. I will ask for a discount then as they have completely ripped me off on parts lately
I’d say each car is a bit different on it’s requirements.
Na cars you can go to about 65k but if your adding power exhaust is the thing you’re going to want to really invest in. Plugs on NA cars usally hold up well. Carbon can be one of the main drags on NA cars so inspect the plugs at 35k but generally replace them at 65k
Now turbo cars you want to keep on top of the heat range and interval depending on how much boost. check out every 30k or so.
Supercharged cars. Almost the same but since supercharged cars make boost much sooner and the boost curve tends to be fast and low rpm. You need to keep with a good performance plug. Again depending on the amount of boost go a heat range cooler.
The plug tighten specs usually are more plug dependent than motor dependent as there is usually a crush washer on the plug. But for safe sake. 25lbs is good. Some go a step further 25lbs then after a few heat cycles check but I’ve never had an issue just going 25lbs and letting that be it.
I change mine every 30k maybe a bit over the top but I do think I can feel a difference once I’ve changed them !
25lbs is whst ive always done mine to as well !
That’s nuts 
. I will be comparing as well. One should at least stick to changing them every 6 years per audi just in case the thread metals oxidise and stick, for peace of mind. Can’t hurt tracking misfires, some cylinders being more prone to those.
I change mine every 30K miles and really like the NGK Ruthenium plugs. I’m not a believer in magic plugs but the car idles so well with them. I used to have a 600rwhp RX7 with a massive Garret hybrid GT42 turbo. I’d change the plugs every 3K miles!