Where do find o-rings and misc small gaskets

[mhost2]

I have a 2002 Pathfinder 4wd Chilkoot edition

In a few weeks I will be replacing the upper oil pan gasket and the rear main seal. My plan is to replace all gaskets and o-rings and a few various small part while I have pretty much everything out of the car.

I have the service manual and looking at the steps, the pictures show several o-rings and gaskets that I will get to in the job, but it has no part numbers.

The sites I use to find parts for my specific car does not have any o-rings or gaskets (other than very big/common ones). Where do people get these? And how do you know which to get?

I know I can go to nissan service centers, but they charge minimum $10 per o-ring.

I've noticed on amazon I can find variety packs of generic o-rings. Should I just get something like that and just replace with the closes matching size?

Thanks.

[EdBwoy]

I have found this site to have a very good breakdown of parts, at discounted prices compared to local dealerships.
https://www.nissanpartsdeal.com
Once you find the part number, you could always shop around online as long as the total cost for checkout plus shipping (Canada, ouch!) makes sense for you.

I have bought an assortment of both metric and standard O-rings that I have used with some success, but when it comes to internal engine parts, I prefer to just go by what the engine manufacturer recommends.
Of course, I compare the OEM parts I receive to what my generic parts are. Some look similar, but for the cost of a 3 Dollar O-Ring, I take the peace of mind and assume they have the right seal material for the fluids they will be in contact with, and at the right dimensions.

[mhost2]

Thanks.

The diagrams on that site are definitely useful.