Beetle Oil Change Interval
My engine specs:
1600cc Dual Port Type I in a ?73 Beetle 34PICT3 Carb (non smog) SVDA distributor with Pertronix and C.D.I. Bypass oil filter mount (replaces oil cooler flange) Stock exhaust and heater boxesHi All! I have been told for years and have read in auto manuals to change the oil every 3 months or every 3000 miles. You know, "Pay me a little now, or a lot more later." Later on they started saying change it every 5 months or every 5000 miles for light duty service.
John C. of Aircooled.net recommended that I change my Beetle's oil at least every 1000 miles since it does not have a full flow filter. I have nearly always tried to change the oil at least every 850 miles to 1150 miles.
But here's my question, I only drive my ?73 Beetle about 350 miles every 3 months. Should I continue to change the oil every 3 months or could I wait longer? I was thinking of changing it every 4 months provided that I am using the right weight oil for the ambient temperature. I use 30HD Castrol for hot weather,
20W 50 or 10W 40 for moderate weather, and 10W 30 for cold weather. I am concerned about sludge build up and acid formation in the oil. I was also thinking of using one quart of synthetic oil and 1.5 quarts of conventional oil. I thought the 1 quart of synthetic oil would be a good additive, and help with start ups. The one quart synthetic would only be used during moderate or cold weather 85 degrees F or under. Would the 1.5 quarts of conventional oil still help cool the heads? Thanks! Any help is appreciated!