Re: oil change intervals
 

The owner's manual with my September 2017 bike is the same date and part # as yours.

From my own experience, the plugs were still usable at 15,000 miles. As mentioned, I did check the gaps at around 7,500 miles and they were all still within the 0.8 to 0.9mm spec, one was at 0.9 so I tweaked it back to 0.8mm.

Plug wear will depend a lot on usage - as I ride purely for leisure, my bike doesn't see much town riding or short journeys, and always gets the chance to run at its proper working temperature, which probably gives the plugs an easier life. I rarely rev it much above 7,000 too.

Re: oil change intervals
 

Other plugs would definitely fit - the thread length is exactly the same as the ordinary NGK CR plugs used in previous generations of SV and there would be no clearance issues because the conventional plugs have shorter electrodes.

However, the long nose of the MR8E plugs not only moves the spark kernel further into the combustion chamber, it also helps plug cooling as there's more ceramic to conduct heat.

I would think you'd need to use a cooler grade of plug like the CR9E if you were experimenting with alternatives.

Re: oil change intervals
 

All interesting information. So what can you do, if you don't want to invalidate the warranty, but replace the plugs every year or 7,500 miles as stated in the owner's handbook ! Must say I have never known plugs being replaced this often.

Re: oil change intervals
 

Most spark plugs in modern vehicles have a longer projection on them to take spark further into combustion chamber. The ones on wifes Honda Jazz have a projecting iridium electrode on the ground electrode as well as centre electrode and if you use the proper Honda ones a set of 4 cost almost £140...I just checked the spec for heat range, spark position, thread length and got NGK ones at about £12 each, and they have been in for about 40,000 miles now. EBay is awash with dodgy spark plugs, so I buy only from reputable places -if it seems too cheap to be true it probably is. Copper nickel alloy core on genuine plugs takes the heat away from tip, many 'too cheap to be true' plugs probably have steel cores, which can melt. Proper iridium plugs also have special coating on threads to make them easier to remove after they have been in for a while.

As for bike engine oil, the oil is shared with gearbox and clutch, so has a hard life and dirt from clutch plates can contaminate the oil. Also bike engines more highly stressed than car engines.

Re: oil change intervals
 

Car oils have had the metallic based additives reduced over the years in the interest of catalyst durability (in-use emission compliance). The extreme pressure additives commonly used for contacts such as cam/tappet and also gear teeth typically contain zinc and phosphorus (see ZDDP). Bike oils will contain 2 or 3 times the phosphorus levels of modern car oils in order to prevent wear of gear teeth in the transmission. There's also the clutch slip aspect, see JASO-MA etc.

Re: oil change intervals
 

I put 2% Liqui Moly 2591 (60ml) in my SV every oil change.. £8 for 300ml normally.