It is not a unsual for owners to use non oem parts for common service items. The fram filters, as long as it is listed as compatible with the ap2 (2007) s2000 will not be a problem.
Generally however, most owners will rely on oem for many of the common parts, while it is generally the various oils and lubricants in which we are more likely to use an aftermarket brand.
Here is the Honda brand filter
Honda Part# 15400-PCX-004. This is the oil filter specifically for
here is a good website to look at in the future, it is where just about all s2k owners do their maintenance shopping.
The dipstick is fairly easy to locate, when facing the engine it is a small black rectangle on the drivers side of the engine block at the near corner.
Always check your oil after the engine has has a chance to cool completely and is parked on level groud.
FYI the difference in oil between the lowest line on the dipstick and the high line of the dipstick is appox 1 quart of oil.
Finally you should always remember to replace the oil drain plug washer with a new one every time you change the oil as it is a one time use part. THey are available at the website I listed above.
Hope this helps.
I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_cd01d4e4178e5a11