High mileage fluids.

That's awfully much; I'd be really worried if I had consumption like that. My 98 Stratus with the 2.4 engine and ~175,000 miles uses 1 quart about every 3K miles. I am actually running this "High-mileage" oil right now (Mobil-1 synthetic, 10W30). I was hoping that it will reduce consumption, but no - I added a quart recently at 3K miles, no change. Since it doesn't reduce consumption, I'm not going to use it again - I tried it only because I thought it would. I'll switch back to the long change interval synthetic Mobil-1, top it off regularly, and change it like before, once a year. I was actually wondering about the synthetic Rotella 5W40 - does anyone here have an opinion about it - will it reduce consumption? And is it OK to use in that engine?

If it is still SJ rated it probably provides the best protection for your tappets of any mass market oil (other than a comparable oil like Delo synthetic) however I have no experience with your particular engine, it may or may not prefer a 40 weight oil to a 30 weight.

I run it in the Porsche (but then again, German mfgrs. tend to spec heavier oils) and it seems happy with it; can't comment on consumption however as I suspect it leaks more than it burns.

nate

Don Stauffer in Minnesota wrote in news: snipped-for-privacy@d55g2000hsg.googlegroups.com:

Modern engine oils are formulated to combust with very little residue. This is in order to avoid damage to emissions components.

It would have to be an awful lot thicker to make a difference in consumption. And if it were that thick, your bearings would have a hard time of it on startup, which is when most bearing wear happens.

My own experiments show zero difference in oil consumption between

0W-40, 10W-40, 10W-30 and 5W-30.

I notice Mobil now sells a 5W-50. That one has me intrigued, but I wonder about all those viscosity improvers...

I think modern oils would only foul the plugs if consumption levels got high enough to result in actually wet plugs. By that point you'd be blowing an opaque smokescreen out the tailpipe, even with a cat.

Steve wrote in news: snipped-for-privacy@texas.net:

And most (if not all) Honda products.

It's also my understanding that the additive "organo-moly" has largely substituted for ZDDP in modern oils. There is still more ZDDP than there is moly, though.

Steve wrote in news:dOednQgKkOM3DTrbnZ2dnUVZ snipped-for-privacy@texas.net:

That's what everyone is saying, and there are anecdotal stories to that effect.

The API is on record as stating that SM oils work just fine in flat-tappet engines, even in those going back to before WW2. This has been tested by the API.

However...

There has never been actual testing of MoS2 (moly) aditives to see if they produce "anti-wear pads" like ZDDP does. Right now nobody really knows just what MoS2 does to prevent tappet wear, or to what degree it mimics ZDDP.

Diesel oils still carry unreduced levels of ZDDP, since they are intended only for use in vehicles without gasoline-style catalysts. What you need for a gasoline engine, though, is a "cross-over" diesel oil. Cross-over oils carry an additional designation in the API donut: API Service CI-4/SL. The "CI-4" is the diesel rating, the "SL" is the gasoline one. They have the necessary additives for proper functioning in a gasoline engine, but also have the old levels of ZDDP.

Cross-over oils are NOT for use in _catalyzed_ gasoline engines!

Yeah, my first cars were forties and fifties vintages. Much of the progress WAS made in the 70s. Heck, the flathead Fords needed bearings and rings every 40-50K.

I am using Rotella Synthetic 5w40 in two engines right now- a non-rebuilt '69 440 Magnum with 150k miles in my '69 R/T (weekend/fun car) and a "built two years ago with 18,000 miles so far" 440 Magnum clone built in a '71 block (my daily driver). No complaints, and the

5w40 seems to be a fairly happy viscosity, although I'd prefer a 5w30 or 10w30 since both of the engines have high-volume oil pumps and are quite "easy" on oil as far as heat loading so anything over 30 is just a waste of power.

Rotella Synth is currently rated SL, so its already got reduced zinc, but it still has the CI-4plus rating (a diesel engine rating actually) which from my reading on the subject implies tappet protection as good or better than an SJ rated gasoline engine oil. Rotella-T NON-synth has already gone to SM/CJ-4, so my fear is that very soon the SL/CI-4plus Rotella Synthetic will also transition to SM/CJ-4. When that happens, I'll be stocking up on GM Engine Oil Supplement, I suppose :-/

No oil will "reduce consumption" very much if you're burning oil past the rings or down the valve guides, at least not unless you also go to a significantly heavier weight oil like maybe a 20w50. Going to a heavier weight oil has many downsides- oil pressure may indicate higher and oil burning may decrease (a little), but oil distribution through the engine can be much worse with lower flow rates through the bearings and other areas where a thinner oil would flow more volume of oil and carry away more heat. Thicker oils also put more load on the oil pump drive (and in extreme cases can break oil pump drives in some engines) and waste gasoline because it takes more power to drive the pump and for other parts to shear the thicker oil. Some oils may reduce consumption a little if you are LEAKING oil, not burning it.

You're kidding! Seriously, I've spent very little time looking inside Honda engines. Flat tappets are a significant energy waster in any engine, and the big push to roller cam followers was to boost engine efficiency. Better performance (because the engine designer can use a higher lift-rate cam profile with a roller follower than with a slider) was more of a side benefit. I find it hard to believe that Honda is that far behind the technology curve. I don't like Honda cars much, but I've always believed their engines were fairly advanced technologically.

Of course they'd say that, and its pretty meaningless really. As I pointed out in another post, even flat tappet engines with very low spring pressures and mild, mild cams can run without much in the way of high-pressure additives like ZDDP. I wouldn't hesitate to run my '1969 side-valve 7:1 compression flathead Plymouth engine on an oil without much ZDDP, but no way in hell would I run a 60s/70s muscle car engine with a lot of lift and fast lift rate and really stiff valve springs on an oil like that! Nor a more modern performance engine like the Porches mentioned earlier.

Check out some articles on the CompCams website. Since they sell

*mostly* high-lift fast-lift-rate cams and they have a warranty on them, they're in a pretty good position to assess the effects, and they claim to have seen a spike in cam failures that corresponds to the reduction of ZDDP. Here's one article:

That is actually not true- here's a page straight from the Shell Rotella FAQ pages:

Diesel engine oils ARE reducing ZDDP, since it contaminates the diesel engine catalysts now hitting the market just like it does gas engine catalysts. They are just reducing ZDDP more slowly than gasoline engine oils because (so far) the catalysts used with diesel engines are a) less numerous, and b) less sensitive to ZDDP contamination. But the trend is there.

LOL. I'm in both worlds. I had a 70 Buick for a winter beater. Worst winter car EVER. Damn thing would run fine in the summer when I needed it, would die in different ways every time it hit 20 below.

We've got a 90 Beretta that just won't die, and I can pretty much rebuild in my sleep. It's been semi-retired, because the backseat isn't big enough for two carseats. As a result, we bought the Subaru for as close to a car-appliance as I can go... but it's still a stickshift. :)

I've only ever bought one new car... my 2001 Trans Am. I think I'd only get rid of it if I could get a Vette and had to prune the fleet down by one. I beat the hell out of it, yet can't stand to drive it in the rain, and even have the original plugs in a baggie for when someone wants to restore it in 30 years. :)

Ray