Castrol Syntec 5W50

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Apr 7, 2005
Bay Area, CA
I used to use this oil in my 95 Montero. This 5W50 weight often was the only weight synthetic available in the parts store.(mid to late 90's) I wanted to use Synthetic for my new truck so I used this. After a while the other grades became more available (10W30).

What is 5W50 for anyway? Why was it the only weight the store stocked?
I believe the original Syntec weight available in NA was 5w50. The same for QS Synquest and possibly Pennzoil Performax. I believe it was a "one size fits all" approach. Castrol eventually introduced a 10W30 because people wanted what their owners manual specified. I wouldn't worry about having used the 5w50. I'm pretty sure I read some good UOA's in an Audi using it. Do a search and see. Good Luck.
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