Blue smoke

[Norbert Drager]

Dear 356 experts,
my C has suddenly started to blow huge clouds of blue smoke from both exhausts on acceleration. On my last trip of 500 miles it ran beautifully without smoking. The problem started immediately after a full oil change with the usual Castrol SAE 40. I also changed the filters in the standard by-pass and full flow. I have done this service for many years without ill effect. What could be the cause? For any suggestions I would be very grateful, before I repeat the process with new oil and filters. Greetings from Norbert in South Africa

[Wes Bender]

How high on the dipstick is the oil level? Changing the oil and filters was the only thing you did, right?

[Tim Berardelli]

Does Castrol 40wt have the required levels of ZDDP, 1200ppm?

[Norbert Drager]

Hi, the oil on the dip stick is one millimeter above the top mark. Apart from oil and filter change, I just checked the tappet clearances, but they were ok, compression test after it started to smoke also showed no deviations. I have used Castrol SAE 40; API SF successfully for years, also in my 1303 Beetle Cabriolet and change the oil every 1500 miles. To be honest I have no clue if it has the required levels of ZDDP, 1200ppm.

[Dick Weiss]

Norbert,

I've used Castrol 20/50 for 35+ years since the straight weight oil was kinda deleted or hard to get as most FLAPS sell the multi-weight
oil by various mfgs.
It's been found that the Castrol GT has the proper ingredients for "lubing" the flat tappets if the oil changes are followed via the owner's manual. I also use it in my 4-cam and there hasn't been any wear showing on the 'drag levers' or the cam lobes during a teardown.

Dick

[Ron LaDow]

Norbert,
You mention you've done the service for 'many years'; is there a chance you're reached the service limit of the rings? How many miles in those years?

[Norbert Drager]

Ron, thanks for your reply. I also thought that rings could be the problem, but with correct compresson values and the sudden onset of the smoke straight after an oil change, I wondered if something else might be the cause.
Regards Norbert

[Dick Weiss]

Several places for leaks; Warped valve cover(s), worn valve guides + valve stem clearances/'barrel-shaped'), pushrod tube seals (tubes weren't slightly stretched & no cracks in the bellows), cylinders not seated w/equal heights and their seat depths not matched equally w/in .0004-.0005" (if fly-cutted), and finally the vertical cheese-headed screws on each side of the intake manifolds holding the side-plates to the heads