Re-Brake in using CJ-4 S/M OIL

[Harry L.]

I don't think that my 66 427 engine ever had the correct break-in period, when the comp cam was put in. The year was 1989. I bought this car after the cam was in with maybe 500 miles on. I always used API 10 W 30 since 1989. Never had any problems or leaks of any kind. A year ago I read Duke's article,and changed my oil to API CJ-4 SM. My question is, should I add some EOS or just go on using the CJ-4 AS IF THAT IS ALWAYS WHAT I HAVE BEEN DOING ALL ALONG? DUTCH

[Duke W.]

Re: Re-Brake in using CJ-4 S/M OIL

Most lobe failures occur early in life, so if it hasn't happened by now, it's probably okay. Current CJ-4 has a about the same amount of ZDDP as S-category oils before circa 2000 when SL had a 1000 PPM limit on phosphorous, which limited ZDDP.

So I see no need to add additional ZDDP in any form.

Adding a bottle of EOS for initial engine break-in with a new cam and lifters is cheap insurance, but it's not necessary beyond that with OE cams or aftermarket cams that don't have ridiculously high dynamics like the Comp Cams XE series.

Duke

[Joe L.]

Re: Re-Brake in using CJ-4 S/M OIL

I don't think that my 66 427 engine ever had the correct break-in period, when the comp cam was put in. The year was 1989. I bought this car after the cam was in with maybe 500 miles on. I always used API 10 W 30 since 1989. Never had any problems or leaks of any kind. A year ago I read Duke's article,and changed my oil to API CJ-4 SM. My question is, should I add some EOS or just go on using the CJ-4 AS IF THAT IS ALWAYS WHAT I HAVE BEEN DOING ALL ALONG? DUTCH

Dutch------


I don't think you need to add any EOS at this point. I think you can just continue to use the diesel engine-rated oil you've been using. However, if you want to add a 1/2 pint of EOS to one oil change, I don't think it would hurt anything.