Recently acquired an 86 Samurai with a 1.3L 4 cyl mileage unknown (probably around 100K), would like to do a gentle cleaning with via oil. The valve seals were pretty hard and brittle which caused it to smoke at startup. Changed the valve seals and it doesn't smoke but I've noticed it's using oil, no leaks that I see. So probably pretty dirty inside. Of course with a vehicle like this economical works the best. How about ST 10w-40 syn blend at 3K intervals?