[DE Nichols]

Both oil and plugs have made major advancements since 1988 and the printing of your owners manual. If you are using the exact same plugs and oil then I'd continue as you are. But if using an improved oil or plug I'd up the interval slightly. Depending on oil, 5k-7k might be okay and plugs could be 10k-20k. Some plugs can go a lot more but doubt you'd want to use them simply because of cost. I certainly hope you are changing the oil filter as well. It too might be an improved version. Things have changed. Need to change with it sometimes.

I don't know what kind of spark plugs go in this. I know you said NGK, but are they, copper, nickel, platinum, or iridium?

At least in cars, I've found that iridium's last 1/2 as long as manufacturers say. 50k miles, not 100k miles. Platinums last 20k miles not the 50k miles that they say.

Conversely, the spark plugs in the 90's sometimes were no good in 10k miles and a lot of those cars hated platinum so you couldn't get 20k miles.

Really good copper plugs can last 20k miles these days and 20 years ago they could be shot in less than an oil change. When buying cheap copper plugs to save money on a modern car which needs better, I think they're just that. They're made cheaply, they don't last, and they cause issues.

Forgive me for adding my perspective as a professional car mechanic instead of specific to motorcycles.

Long story short, you think they're lasting longer? You're buying NGK. They are quality. I'm sure you are correct. Like Aphrodite was saying in post 2. You're doing great.

 

[DE Nichols]

I keep stabil in mine all the time since I have been doing this line haul gig. Sometimes I am lucky to have been home to ride one time a month. Keeping your tank full anytime you park it is always a good thing no matter what time of year.

But anywho sounds like your on the right track, keep and maintain oil level and tire pressures.

Forgive the bit of a derailment, but how good is Stabil? I only have one gas tank which has been sitting, but it's been sitting for years. It's attached to an engine I haven't afforded to replace.

Stabil says that the product is only good for 2 years...I still have 90% of the bottle, do I really need to toss that bottle and buy another? Except for when a contract had me largely away for 11 months, I have been good about adding more Stabil a few times a year and the gasoline doesn't smell old like cars which are towed in for me, and I think, "OH, here's the problem!" The fact it smells fresh has me somewhat unconcerned.

 

[DE Nichols]

Spark Plugs - NGK DPR8EA9 (These are standard plugs and what the current NGK website says to use which kind of surprised me since it's the same plug they recommended 30 years ago. Also, I had a 2nd gen Miata with the "wasted spark" design and I tried the Iridium plugs which I found were overkill and offered no advantage - the standard plugs ran just as well at a fraction of the price. I use NGK in everything, cars, mowers, weed eater, leaf blower, etc. I also like the fact that no anti-seize is necessary with the proprietary coating.)
Oil - AMSOIL 10W/40 Metric Motorcycle Oil
Oil Filter - NAPA Gold 1358 (made by WIX)
Coolant - Honda Long Life (same as the Honda motorcycle coolant but in a bigger jug at a cheaper price.
Gas - Top Tier (Citgo, Exxon or BP) for long trips and Citgo non-ethanol which I keep in a jug in the garage for my day trips. I use mid-grade 90 octane which is probably overkill but that is all I can get in the non-ethanol, so I stay with that octane. I try to never use non-brand gasoline.

I'm kind of OCD. Every time I put my Shadow on the jack, which is pretty often, I check the oil level, coolant level, chain slack and lube (Chain Saver Spray for chains with o-rings). And I look for the possible leaks. So far, no problems anywhere.

You're so me! I check it all all the time. I can only find nonethanol gasoline for 89 octane and my motorcycle requires 91 and I don't want knock so...sometimes I mix 89 and 93. Not sure if that works, but it seems right. When I just run 93 I can smell it runs richer. Too much octane does that. Sure, more power now, but more wear on the engine too.

I've ran 89 just to see and I run out of throttle at the same speeds where I still have throttle left, so I know it's running a little weak.