The '06 RSX Type-S and the '06 Civic Si have the K20Z1 and K20Z3 engines, respectively. Though both engines may be similar, they actually have different viscosity requirements.
Both Amsoil and Mobil recommended the 5w-20 for the K20Z3 equipped Civic Si and 5w-30 for the K20Z1 equipped RSX Type-S. Tennisjon needs to check his user's manual to verify the recommended viscosity.
5w-30 may be used in the K20Z3 if one desires, though I personally doubt there will be a significant increase in engine life when 5w-30 is substituted for the recommended 5w-20. If Tennisjon is interested in using 5w-30, he should use 5w-20 until his 5-yr/60,000 mile powertrain warranty expires, then switch to 5w-30 to avoid hassles with Honda in the event of a warranty claim. My memory from prior conversations with Tennisjon on AcuraZine tells me that he does not service his own vehicle, and service centers are generally hesistant to install an oil viscosity other than the one recommended by the OEM, purely due to liability concerns.
My personal opinion only: Synthetic oils do not necessairly constitute a longer drain interval. There are other factors that will determine oil life other than the added oxidation resistance, higher TBN, etc in synthetic oil. For example, fuel contamination from short trips due to the engine rarely seeing normal operating temperature may justify the need for a shorter drain interval regardless of oil type, due to contamination.
The PureOne issue should really be put to death. They may be more restrictive than other filters but their flow certainly meets/exceeds OEM requirements, I'm sure. If flow is really important to one, they should look into the Napa Gold or Wix branded filters.
Although I personally do not see the need for a synthetic, it may not be a bad idea to consider one in this case. Pennzoil Platinum 5w-20, Mobil 1 5w-20, or Amsoil XL 5w-20 are all good choices. Napa Gold/Wix or Purolator PureOne Oil Filter. Change the oil when the Maintenance Minder System reaches 5%. Get an oil analysis after the second or third oil change.
If you're still have a shop do the maintenance, Walmart TLE does synthetic oil changes for $40 with the brand of your choice (M1 or Pennzoil Platinum). Just buy your Napa Gold or PureOne filter and bring it to them. Same goes for Jiffy Lube, though they use Pennzoil Platinum only.
PS- Consider switching your transmission lube to either Redline MTL, SF MTL-P, or Amsoil MTF at the first oil change. Jiffy Lube or equivalent usually charges less than $30 for labor if you bring the fluid.
