LS400 Spark Plugs

[Tinonline]

A few months ago at 75k odd miles I replaced my spark plugs from my mk4.

I couldn't see any evidence of past replacement and was puzzled by very worn plugs bearing the NGK brand in pale blue. They looked old. I did a write up; that's in the how to section.

What I put in were Denso plugs and that's what I'd expected to remove. All the mileage checked out.

However, having a trawl through the handbook I spy that original fitment listed as Denso SK20R11...and NGK IFR6A11.

That solves the riddle: I removed the original NGKs.

[MLW]

Did you notice a significant improvement after the new plugs were fitted?

In the old days when plugs were replaced each year, one often noticed a bit of a pick up after a plug change. As a bit old school I often worry about 60k+ mile plug changes, although I know that they are much better these days.

[Tinonline]

Hi

I combined the plug change with an air filter change and adjusted the throttle cable slack. All around I felt an improvement. 

The iridium plugs are designed to last for ages. The ones I removed looked quite worn but to be fair performed fine and performance and mpg were excellent.