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Discussion Starter #1
Hey guys so end of the summer I changed the oil on my 67 Pontiac 400, I used a Castrol 10w-30. Ran it for a bit, did some short drives with it not much running. Now it sounds like there Is a slight tap. Could this be from the oil? There was a heavier weight oil in it previously. I am changing the oil again and putting a heavy weight back in. But did I do any damage? Any ideas or comments welcome
Thank you in advance
 

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What Matt said. Castrol doesn't have the ZDDP you need for cam protection. I seriously doubt you got a flat cam due to the stock configuration of your engine and limited and easy use it gets. More than likely a hydraulic lifter that is bleeding down. Use a good oil like Brad Penn or use what you want with ZDDP additive.
 

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Also it's possible that the heavier oil was masking a problem that was already there. That's an old "dishonest used car dealer trick": put really heavy/thick oil into an engine that's making some noise and it'll quiet it right down, usually just long enough to get the car sold and off the lot.

Bear
 

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Discussion Starter #6
Thank you guys!! made me feel a lot better, I changed the oil and added that and we shall see what happens comes spring time!!!
 

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Before my motor was gone over and it leaked I used Valvoline 50W racing oil with ZDD in it. I then looked for 30 or 40W couldn't find it then I did find 30W Valvoline racing oil with ZDD at a garage they can order it..... My plan was to finish my stock of ZDD but I keep finding it on sale and buying a couple here and there. I have enough for a few years yet and I would imagine I will see it on sale again low enough to buy a few more.
 

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I would not use racing oil in a street engine. It does not have the additive package you need on the street for engine protection. It is meant to be dumped out after each event and does not have the anti-corrosion properties you need in a street driven engine where the oil is in the pan for a few months (or more) at a time.
 

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