There are a few ways to find out:
1) Search this forum- there are numerous threads on this subject
2) Search for a downloadable version of the Bentley manual. This will provide you with the correct weights and approved oil grades/types for your engine. Also included is a scale of weights depending on what climate you're in.
3) Search for "Bob is the oil guy" on a search engine. Tons of information on that site.
Good luck on your search.
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