I just bought a new GS350 and hopefully, plan to keep it for 6-8 years. What are people's experiences with proper engine break-in for new cars? Does it really matter anymore?

 

I was told that speed is not important. What really matters is that one should vary the speed for the first 1,000 miles or so in order to allow the valves to seat properly.

I have never followed rules very rigorously on any of the various new cars I have owned throughout the years and never had any engine problems.

 

I use the 1000 mile rule. Many use the 500 mile rule. -I have driven my Toyota and Lexus vehicles over 100k miles.

The key to intial break in are very simple:
-Keep your freeway cruising speeds below 65mph
-Keep engine (RPM) speed below 3-4k
-Avoid jackrabbit starts.
-Allow the car to warm up 30 seconds (enough for oil to circulate from pump and throughout motor) before you start...don't go longer than that.
-Avoid using the cruise control during long periods of driving, try to vary your speed.

To date, I have no problems with my engine's valve seals leaking prematurely (I always pay attention to this looking at other people's cars). Follow the factory suggested oil change intervals. I like to use the Lexus 5k interval. Make sure you use a quality oil filter and proper oil weight at each service. Driving your car using those simple steps above allows proper seating of the seals in your motor.

 

For me, I've had my car for 3 days and I've been keeping the RPM below 3k. My daily commute is at least 40 miles and I would say 65% of that is highway/expressway so the fastest I go is 70MPH just to keep up with traffic, I wish I could keep it slower but I really think that engine RPM > speed.

 

Break in periods are controversial.

"Liberals" think the break-in period is obsolete to current technology.

"Traditionalists" (such as myself) believe that break-ins are not speed dependent. Just keep RPM below 4000, vary speeds, and prevent sudden acceleration; all within the first 600 miles. The GS350 at 90 mph will not break 4000 RPM if conservatively accelerating...

 

I totally agree. Engine RPM, once again, is more important IMHO.

In addition, the 3GS is very powerful that it isn't hard at all to keep the RPM below 3000.