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Stang70Fastback · 07-02-2018, 05:45 PM

In all seriousness, here's my reply based on ZERO research, and only one anecdotal example:

My old Subaru Outback had an EJ25. It was old. 260,000 miles old. I always babied it, having been told be our previous mechanic who had done the head gaskets many years ago that we should go easy on it to avoid them going bad again. As a result, I rarely went above 3500 - 4000 RPM in that car.

One year I threw caution to the wind and did an autocross. With a co-driver. That meant a total of 12 runs thrashing the hell out of the car.

After that event, the engine ran SO MUCH MORE SMOOTHLY, it blew my mind. I hadn't even thought about that. I was solely concerned with blowing it up, and actually thought it was running "fine." After the event, it suddenly revved more quickly, idled more smoothly, and seemed to have better throttle response. In any event, that kind of sold me on the whole "a bit of hard driving every once in a while helps clean out the engine" thing.

I also know that every new car's break-in procedure mentions that you should avoid extended, steady-state cruising during the first thousand-or-so miles of break-in, and avoid using cruise control. This is because they want you to work the engine across the entire rev-range, and not sit at one constant RPM. While I don't officially know the reason for this, someone once told me it was because if you were to break the engine in at one RPM, it would develop a kind of "flat spot" where it would be happy running at that speed, but not quite as happy at the other speeds.

Both of these things I know are MUCH more applicable to older vehicles than modern ones, but my brain still posits that if you NEVER really rev the car up very much, you still will get SOME more deposits than you otherwise would burn off. Likewise, if you NEVER rev the engine up, I posit that - although to a MUCH less, and maybe not even noticeable extent these days - the engine will probably be slightly less happy to suddenly run at those higher RPMs.

Again, this is all based on my one experience... so really it's meaningless, but I thought I'd share.

07-02-2018, 05:45 PM	#12
Stang70Fastback A.K.A. Starlord Join Date: Oct 2013 Drives: 2015 Series.Blue Location: Illinois Posts: 1,842 Thanks: 845 Thanked 2,102 Times in 835 Posts Mentioned: 30 Post(s) Tagged: 3 Thread(s)	In all seriousness, here's my reply based on ZERO research, and only one anecdotal example: My old Subaru Outback had an EJ25. It was old. 260,000 miles old. I always babied it, having been told be our previous mechanic who had done the head gaskets many years ago that we should go easy on it to avoid them going bad again. As a result, I rarely went above 3500 - 4000 RPM in that car. One year I threw caution to the wind and did an autocross. With a co-driver. That meant a total of 12 runs thrashing the hell out of the car. After that event, the engine ran SO MUCH MORE SMOOTHLY, it blew my mind. I hadn't even thought about that. I was solely concerned with blowing it up, and actually thought it was running "fine." After the event, it suddenly revved more quickly, idled more smoothly, and seemed to have better throttle response. In any event, that kind of sold me on the whole "a bit of hard driving every once in a while helps clean out the engine" thing. I also know that every new car's break-in procedure mentions that you should avoid extended, steady-state cruising during the first thousand-or-so miles of break-in, and avoid using cruise control. This is because they want you to work the engine across the entire rev-range, and not sit at one constant RPM. While I don't officially know the reason for this, someone once told me it was because if you were to break the engine in at one RPM, it would develop a kind of "flat spot" where it would be happy running at that speed, but not quite as happy at the other speeds. Both of these things I know are MUCH more applicable to older vehicles than modern ones, but my brain still posits that if you NEVER really rev the car up very much, you still will get SOME more deposits than you otherwise would burn off. Likewise, if you NEVER rev the engine up, I posit that - although to a MUCH less, and maybe not even noticeable extent these days - the engine will probably be slightly less happy to suddenly run at those higher RPMs. Again, this is all based on my one experience... so really it's meaningless, but I thought I'd share. __________________ . Check out my blog, read all about my BRZ adventures, and oogle my sweet cell-phone photos! You can also find me on Instagram, and on Facebook.