Piston Slap Concern
 

Hey! I went through all relevant forums about piston slap, but would like a little more up-to-date information and more opinions.

I have a '07 with 130k miles. I haven't ever heard piston slap until after an oil change from the Honda dealer and a valve adjustment. The car was bought at 127k miles and had a loud idle, so I couldn't hear anything until now. The valves were on the loose end all the way around, the idle now is much smoother and quieter, minus the piston slap. I assume the dealer used Mobil1 for the oil.

The noise is exhibited when cold and is gone/faint when the car warms up. My reasoning is that forged pistons usually exhibits slap, but it's only on cylinder one for me. I've seen a comment that said it's normal among S2000s, is it actually? Has anyone ran a different oil that has mitigated the slap?

The valves should be on the loose end of the spec all the way around. What did they set them to? Valves tighten in use. If you can't hear them they're too tight. The DBW engines starting in 2006 are very susceptible to burning the exhaust valves if clearance is too tight. To avoid burning the exhaust valve set to 0.001 over (looser).

Intake: 0.010"
Exhaust: 0.012" "one thousandths over"

What makes you assume the dealer used Mobile1, and in what grade?

-- Chuck

Honda pistons are not forged. Piston slap is hard to diagnose, but it is generally harmless either way. You are right that the sound can be reduced with different oils, I would run an oil with higher levels of Moly and see it makes a difference, or different viscosities.

I set the valves to what billman recommended for dbw cars, but slightly looser due to it being my first time. They were extremely loose, to the point where I had a lumpy idle/misfire. Don't remember the exact values though. Idle is smooth now and sounds like a sewing machine (minus the piston slap).

I assume Honda uses Mobil1 to formulate their oil like how Toyota/Lexus does. I read it somewhere, so I've been assuming it's Mobil1 in the car right now.

EDIT: Included a video of the idle before valve adjustment.

EDIT 2: Just remembered the car was jerky at low speeds and seemed to stall fairly easily. All of that went away after valve adjustment.

I thought the f20c and f22c came with forged aluminum pistons, at least that's what I found from forum digging and online research.

That's what I've found, just wondered if there was a preferred oil among all owners. I might do an early oil change, just to see.

I use M1 in my 06 S for 15 years now. 200k miles and still doesn't burn oil. I use a mix of M1 0/40 (4 qt's) and M1 0/50 racing oil (2 qt's).
The 0/40 runs on the thin side for a 40w and two qt's of 0/50 brings it up a little but still well lower than the top of the 40w scale. Plus the 0/50 has a shit load of moly at 1300 ppm and a lot of ZDDP all of which helps with reducing friction. I run the oil 7000 miles and when I did get my oil tested(haven't had a test in 90k miles) it always came back good to run longer.
If you are going to drive your S like most of us you will take it to the redline from time to time(which is fun). The S will thin out the oil a little over time so that is one reason I start out with a oil that is in a 40w scale and I like all the friction reducers(racing oil) without going to a oil that is in the 50w zone.
Plus the S can run 5/40 as it says so in the manual(in the winter no less) so if a 5/40 is ok in the winter, a 0/40 will be just fine in the summer.

Rod

Honda F20C engine,

Bill recommends setting the exhaust valves to 0.012"

Make a pot of coffee and read all 375 notes in the thread linked above but you'll find the critical information in Billman's initial post: -- Chuck

Generally harmless. If it starts making noise all the time even after completely warm you should start seeing what is going on there.

Nothing wrong with M1. I run it in every car I have including the s2k which has 165,000 miles and many hours of track and autox use.

Yeah, from my previous research it seemed to be normal and harmless. Billman even said so, but just needed a little more up-to-date info to ease my mind.

I also run M1 in mine and my family's cars, no issues there. I just read something that their weight is usually on the lighter end. Not sure how much moly M1 puts in their oil, but I was looking to move to a different brand that's high in moly as an experiment.