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 boxes
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?
Any help is appreciated!