Hi guys. One tidbit to consider is many brands of oil do not use compatible additives. Switching to a different brand of oil seems to be a common cause of leaks and burning oil, but that can clear up over time. All engine oil has dispersants, detergents, anti-foaming agents, corrosion inhibitors, viscosity modifiers, and seal conditioners. When you change the oil in an engine that calls for five quarts, it actually holds about seven quarts of oil. Two quarts in the passages and hanging up in the heads never drains out during the oil change. The seal conditioners left in the old oil can be attacked by the detergents in the new oil, as an example. Twice I have witnessed people switching to synthetic oil and within a few days the engines developed pretty severe oil leaks. Those leaks slowed down after about a month of switching back to the oil used previously, but they never totally dried up.
Years ago flooding carburetor engines was common. That raw gas washed down the cylinder walls and removed the film of oil on them. If that was not real severe, the gas would vaporize out of the oil during prolonged highway driving and be sucked out through the PCV valve to be burned. Until all that gas was gone, it thinned out the oil and made it much easier for it to sneak past the oil control piston rings and/or the valve guide seals. You would see that as blue smoke from the tail pipe. Blue smoke from leaking valve guide seals typically clears up after five or ten minutes. The thinned oil that was burning is what has leaked down the guides after the engine was stopped last time. Thinned oil getting past the piston rings tends to make the blue smoke worse as the engine warms up and the oil gets more fluid. If it was more severe, that gas in the oil could tear up engine bearings leading to a catastrophic engine failure, so it has always been recommended to change the oil right after something happened to get that gas in the oil.
With electronic fuel-injected engines of today, flooding is a rare occurrence, but we still run into problems when we have a spark-related crank/no-start condition. Most problems cause loss of spark and loss of fuel injector pulses, but if only the ignition system is affected, it is possible for the injectors to still be spraying gas into the engine, and there is no spark to ignite it. Once the cause of the no-start is identified and repaired, it can be determined it that did not affect fuel delivery. When that is the case, the oil on the cap or dipstick will have a strong gas odor. That is when it is extremely important to change the oil right away to get that gas out.
Here is a link to an article that looks at other causes of oil leaks and how to address them:
https://www.2carpros.com/articles/engine-is-leaking-oil
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Thursday, September 6th, 2018 AT 10:29 PM
