Synthetic oil use in mid-years

[Jon B.]

First time user of the discussion board. Be gentle with me. There are no stupid questions, right? I need to know any opinions regarding the use of Mobil 1 synthetic oil in my 67 big block. Are there any protocols about flushing the old standard oil from the crankcase before changing to the synthetic? Thank you in advance for your response.

Jon Bishop (533650

[Duke W.]

Re: Synthetic oil use in mid-years

The primary benefits of synthetic oil are a lower rate of oxidation and a wider viscosity range without excessive use of VI improvers that tend to break down with use. So synthetics are advantageous for the following applications.

1. Extended service intervals - up to 15,000 miles (For example, your're a traveling salesmen with a nationwide territory and you like to drive your vintage Corvette. You accumulate 30K miles a year, but only have to change the oil twice per year.)

2. Applications were oil temperatures consistently exceed 250 deg. F (You take advantage of "open track" events in your sales travels, which allows you to hot lap great tracks like Road America and Watkins Glen.)

3. A single oil that has a suitable viscosity range for both arctic winter cold starts and high speed driving in the desert southwest (You must make sales calls in Minneapolis during the winter and Phoenix in the summer.)

If your vintage Corvette sees any of the above conditions then you should consider a 5W-40 CJ-4 .

For typical vintage car use, which means annual mileage accumulation of a few hundred to a few thousand miles, I recommend changing the oil and filter once per year. If the car is stored during the winter months, do this service before the car goes into storage. If annual mileage is less than 500 and the engine is tight with a good PCV system, it's okay to go a couple of years assuming the car is normally kept inside and away from condensing humidity.

Now, download the following pdf and read the article beginning on page 3. When you have fully absorbed the information you will be able to make an intelligent choice of what oil to use for any vehicle you own (including your lawnmower) and give expert advice to others.

http://stlouisncrs.org/news_files/St_Louis_NCRS_Chapter_July_2011.pdf

Duke

P. S. No, synthetic oil is not more "slippery" than conventional oil despite what all the internet "experts" say.

[William M.]

Re: Synthetic oil use in mid-years

In both cases where I switched an older Corvette to Mobil 1 synthetic I developed leaks that weren't there before. Conventional motor oil for me.

[Michael J.]

Re: Synthetic oil use in mid-years

I only use CJ-4 rated oils in all my older cars with flat tappet type systems. CJ-4 has the correct additive package for older style engines, synthetics do not. I only use Mobil 1 in my 2012 ZR1, but that is a whole different animal and not anything like my '67 L71 for instance. I also buy whatever CJ-4 oil is cheapest, like WalMart or Motorcraft, which has been selling around me for $14.49 for 5 quart jugs.

[Jim M.]

Re: Synthetic oil use in mid-years

Wow Duke, that was quite the article on oil, I'm afraid my brain is on on over load. Think I'll just remember the CJ-4 designation along with the 15-40 weight and call it good for my 69. Very interesting article though, thanks for the link to it. Jim