jdshaw

Just picked up new 2015 RX350. Instruction book specifically states that there is a 1000 mile break-in period, and speed should vary. Question: In two weeks I need to take it on a 1300 mile round trip (95% freeway). Odometer mileage before leaving will be around 350. Obviously I don't want to damage the engine in any way. Thoughts?

raylor4

Vary your speed. Don't use cruise control. We had to do the same thing with our Avalon. Pain in the neck, but we did it.
Ray A.

vlad_a

The very first drive my RX450h took was a road trip.
I picked it up in Philly and drove 400 miles home. I kept different speeds and let the engine RPMs go up and down.

ericsan13

Call me a skeptic, but what is the technical reason behind this break-in period?
-Eric

Mors

What Lexus told me not in these exact words (and that could be wrong, or a very minor part)....if you leave the rpms/mph running at the same speed for a long time, the engine performs better at that speed and performs worse at other speeds - if that makes any sense. I know nothing about engines...just passing along what I was recently told. I'm sure there are much more important factors - such as combustion, etc. that more knowledgeable people can hopefully explain.

raylor4

It's my understanding that a new engine has no wear pattern on the cylinder walls and compression rings, and breaking in a brand-new engine PROPERLY, establishes a wear pattern benefiting the engine's life. If anyone else has any input on the reason for the break-in, please do so here. I'd be interested in the effects on the engine of a 400 mile trip without varying the speed.
I like the idea of taking an off ramp every so often to vary the speed. Wish I'd have thought of that when breaking in the Avalon in '97.
Ray A.

KeithPI

Took my 2 week old 2015 RX on our trip from Dallas to Lake Tahoe. I tried to vary the speeds, not using cruise control. The problem was that it was very easy to let the speed inch way up there, especially on the open, boring roads in Nevada and New Mexico. The RX was an incredible ride for the trip, and the wife & I were very glad we got the new vehicle before making the trip instead of after. I saw an consistent increase in MPG as the trip progressed. Hopefully, there is no long term fallout from the early trip.

lexus114

to properly break in the rings. though i was under the impression that with todays engines this was not an issue anymore.