Spark plug change on 86 Sl560
 

My mom's 86 SL560 has been rarely driven over the past 10 years, maybe 500 miles per year (only 60,000 miles on it). I am getting ready to put it up for sale and it idles a little rough. I'm a decent shade tree mechanic, so thought I'd change the plugs and see if that smooths things out. I just drove the car 500 miles and it ran fine, but seemed to only get about 17 mpg.

Is there a certain brand spark plug that works better than others? I'm assuming Bosch is the brand to use.

Should I expect any strange surprises, like plugs that are impossible to reach or plug wires that have a hidden clip?

I'll probably change the plug wires when I change the plugs. Any recommended brand?

Thanks!