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Originally Posted by JCL (Post 827371) You are assuming similar construction, when in fact the forged piston will have more mass due to the difficulty of machining it. You are also ignoring the effects of silicon which stabilizes the alloys dimensionally. Different alloys are used with each method of manufacturing (due to brittleness). So yes, the coefficient of expansion will change. That is why forged pistons had larger clearances, historically.

Regardless of forged or cast, the piston expands when its temperature increases. I agree that forged pistons have larger clearance but cast pistons expand too.

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Originally Posted by JCL (Post 827371) That is accelerating slowly, not driving slowly. What you want to do is limit the load on the engine, and the rpm. For an engine that goes to 6000 rpm, 2000 seems pretty moderate to me. But if you don't put any load on it it will take a very long time to warm up.

Driving slowly or accelerating slowly, the idea is to limit the load on the engine. As long as the vehicle is moving its 5000+lb weight it doesn’t take much to warm up. Your “very long time” is about 5 min.

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Originally Posted by JCL (Post 827371) They are not direct functions. Load relates more to acceleration than vehicle speed. At steady cruising speeds, there is very little load on your engine. And driving down a hill pretty much proves that they are not direct functions.

They are NOT one to one ratio but they are function of each other.
Maintaining a constant speed on a flat road is a load on the engine (if the engine doesn’t work the car will finally come to stop due to various frictions). Pulling and pushing a mass with a car is a load on its engine. Acceleration is also a load on the engine. Just because the magnitude of it varies and one is smaller than the other one it doesn’t mean it is not a load. In any event, we are talking about piston speed and the speed of the car. As the engine rpm increase so does the piston speed.

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Originally Posted by JCL (Post 827371) While all the above is interesting, the original point was that it comes down to reducing or extending the duration of the warm-up cycle. If you leave your vehicle idling and parked, how long will it take to come to full operating temperature? Now drive it moderately and see the difference.

The point that is not getting across is I never said you reach operating temperature if you idle for one or two mins. what I said is one to two min idling will reduce/eliminate need to add oil drastically. I suggest you try what I recommended ten posts ago for few thousand miles (whatever mileage it took you to add oil to the engine in the past) and see if you can eliminate or reduce adding oil to your engine. I have recommended this to at least four BMW owners and all four of them had a positive result.

But as I said above, I don't regularly add oil to my current vehicles. They go the full change cycle, or near to it, without make-up oil. I will go a two-year change service cycle with the X3 without any make-up oil. And without any idling to warm up the pistons, either. So could it be that maybe idling to achieve better-fitting pistons is not directly related to oil consumption?

How about those Canucks? Great game last night, eh?

Off Topic
 

Incredible amount of build-up to it. We are six blocks from the rink, and about the same from the outdoor celebration plaza. Media everywhere. We walked by a few hours before, and saw the green men party on the street.

I thought the Canucks came out strong, played about even with the Bruins for the rest of the first, and all of the second period, and then took it to them in the third. Boston looked tired by then. Vancouver is a very strong third period team, and they just kept coming. The shots were even, but the scoring opportunities were very one-sided for the Canucks. With that goaltending, either their hard work was going to pay off, or a lucky bounce was going to take it for either team.

We found out Chara can be checked, even if it put Hamhuis in the dressing room in doing it (the cross-check to the head may have been part of that) Bergeron learned that if you put your finger in someone else's mouth he may or may not bite it (who knows what happened?). Vancouver showed that they have depth on the third line. The hits were pretty even, both teams are physical. The refs blew far too many penalties. And TT was amazing.

I am not sure if I am reading this right but the fully syntactic oil is meant to be changed 15,000 miles or one year whatever comes first. I don’t think keeping the same oil for two years is a good idea.

Well, I know quite a bit of people who don’t add oil to their engine after they started idling for a min or two. We will see if “hambone1983” decides to try what I recommended and if it makes any difference in his case.

The full synthetic oil is meant to be changed based upon condition monitoring. 15,000 miles/24,000 km is like a starting point for the algoriths, but isn't a requirement. My vehicle showed 28,000 km last time but I changed it early. I think two years is long enough. There is no one year limit.

Back when the X5 was introduced, BMWNA (only in the US) had a policy of doing a complimentary annual oil change for low mileage vehicles, under their pre-paid maintenance plan. That was only in the US, and it was a marketing ploy. That policy was officially cancelled via BMW service bulletins some time back. Those bulletins are posted on this site if you search.

Not if I can possibly help it. Family does. Last time I waited in the lodge at the Whistler mid station with a glass of red wine and read.