Mobil 1 15-50 and piston slap

[cookie]

So the third tank gave me 24.75 MPG. It looks like in my everyday driving I gained maybe two tenths of a a MPG with the thicker oil. At this point it looks like the payback time would be about 200 years if I was going for MPG alone.

I use the Subie for shopping and work trips in bad weather so there are a lot of short trips and starts. The only reason it gets near 25 is that my wife prefers to ride in it when she works late in SF. I pick her up then and that is 48 miles round trip.

The payback from the Mobil 1 will have to be reduced sound of piston slap and extended drain interval. So far the car has not required any extra oil but the dino I used before would not have until it got older either.

[99obw]

Please forgive me if you gave any of this info earlier in the thread...

 

How long do you plan to extend the intervals?

How many miles on the engine?

Previous oil and interval?

 

Thanks,

[cookie]

I had to go out and look but I have 114,196 miles on it now.

I plan to do 6,000 but I will probably driain the first one at 3,000 to clean it out.

Before the car was dealer serviced at 3,000 miles and got 10-30 Pennzoil if I recall correctly.

[99obw]

Sounds like a fine plan.

 

I was a diehard 3k Pennzoil user before I went synthetic. Though some have had different experiences, my engines' internals were alway totally free of sludgy deposits and evenly colored with a lovely tan patina. I still like and recommend Pennzoil. You probably shouldn't have much to clean. 6k is a very conservative interval with Mobil 1. Mobil 1 cleans the most aggressively of any oil I have used. Engines run long enough on Mobil 1 will look like the day they left the factory.

 

Just as an interesting aside, I did a tune-up on a '97 Hyundai 3.0 V6 tonight. "Free" 3k dealer oil changes with 5w-30 dino, 85k miles on it. Quite a bit of sludgy buildup on the rocker arms. Not the worst I have seen, but disgusting none-the-less. I have to be honest, I was shocked to see that result with faithful 3k dino changes. I thought even the cheapest dinos were better than that. I would give a dollar to know what oil was used.

[cookie]

I would too just so I could avoid it. I used to see a lot of sludge on engine teardown many years ago. I rarely take an engine apart these days bur I may have occasion to soon. I have a 400 Pontiac that's been run on dino that I'm thinking of switching to Mobil 1 because my results have been good. I have a few 400 Pontiac blocks around and I will have to see how they look for sludge.

I have the world's worst 65 GTO and at some point I have to decide which engine to use.

I should have let you talk me into synthetic for the Subaru last year. I think you are right that the regular oil changes with Pennzoil will probably leave my Subie fairly clean. I'll be doing my regular weekend car check tomorrow and I will be interested to see if the oil looks dirty yet.

[99obw]

Oil is supposed to be much better now than it used to be, that's why it surprises me to see such sludge. The thing about Subaru boxers is it's tough to see how the oil is cleaning without removing a valve cover.

 

My mom had a '67 Catalina with a 400 when I was a kid, loved that car. Not a GTO, but still a cool car. The first wrench turning I ever did was at the age of 9 when my mom and I put a timing set on that 400.

 

I try to avoid talking people into synthetic, I try to relate my experiences and make recommendations as to what synthetics I think are a good buy. When people start spending $4-$9 a quart on oil they expect miracles, which is unrealistic. For me synthetic oil is a financial break even, keeps my engines spotless internally, offers better winter cold start, and saves me some time. I won't claim it improves fuel economy for me, as I don't have the data, but the higher viscosity index should save some fuel.

 

A good read related to this thread...

http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=1;t=008243

[cookie]

I think I will be lucky to break even in the end. As you say there will be a bit of effort saved and that's worth something. I do believe my engine sounding more like it should is worth quite a bit to me. The mileage change is so little that it is hard to measure. I tend to try to go to the same gas station and fill to the first click.

Some of the folks on BITOG get much more scientific in thier tests. I expected my mileage to drop a bit so finding that it is about the same is a plus. I think that must mean that this oil is not very far off the Pennzoil I was using before in a warmed up state.

[Setright]

I would like to take this opportunity to express my scepticism with respect to BITOG. The theories are home-brewed and the tests used to verify them are irrelevant for internal combustion engines.

 

For example: The "four ball wear test" is designed to test bearing grease, not engine oil.

[99obw]

I think if you actually took some time to read the forum you would learn a lot. Sure, plenty of people perform home-brewed tests, but it's up to the intelligent reader to take it for what it's worth. There are many lubrication engineers, chemists, and auto techs that post there. The knowledge base of the members is second to none.

 

You know what's ironic? Most of the posters there would agree that the four-ball test is useless for testing motor oil.

[cookie]

Mr. Science it ain't, but many of the posters there know a heck of a lot more about oil than I do. I take it all with a grain of salt, but I have learned a lot there.

I'm not so impressed with the four ball test myself for this application, but some of thier tests are prestty interesting. The auto manufactuers have done some great testing, but that data is not usually available untill it's so old it won't help the competition.

[Scoobaroo]

As long as an oil meets SL/SM specs, there really isn't much difference between them. Use the weight of oil that works best for you.

A few parts per million more or less of a particular additive per quart isn't going to mean squat over the 10 to 20 year life of a car. On paper, synthetics are clearly better than dino oils, but they're not worth an extra $3 to $4 per quart unless you can stomach extending your drain intervals 3 or 4 times longer; 15 to 20k miles.

 

Consumers are suckers for labels. "4X4" oils. "Truck and SUV oils" "High Mileage Oils" "Cold Start Oils". (LOL)

Of course, you pay a premium for slick marketing, and a "specialized" additive package vs. a high quality, generic, off the shelf additive package. Each brand of dino oil is as good as another within about 1%.

 

With conventional oils, the difference between an .88 cent quart of house brand SL/SM oil and a $1.88 quart of major brand oil likely goes to quarterly executive bonuses and TV/Magazine advertising, not beneficial additives.

[Scoobaroo]

As a side note, much of the stuff on BITOG is worthless. His oil filter "flow tests" are performed with room temperature oil. An oil filter will bypass room temterature oil, not filter it. His oil filter cutaways are interesting, though.

 

Yes, the 4 ball test is next to worthless with regard to engine oil. Also, it's been proven that contaminants smaller than 20 microns will stay suspended in oil and cause no engine damage. Therefore, it's useless to obsess and overspend on an oil filter that filters particles down to, say, 10 microns or 1 micron for God's sake.

[Scottbaru]

I used Car & Driver oil in my '01 Sienna, changed it every 7500 per owner's manual. At my last oil change the oil came out black, chunky, and smelled burnt. I put in the cheapo oil I had ready, then turned it in at the end of it's two-year lease. I felt bad that I wasn't giving this car the best treatment, but it was a lease. My brother runs Mobil 1 in his '01 Sienna, doesn't worry about oil sludge.

 

 

Apparently many carmakers are getting reports of burned oil. I've heard higher head temps are to blame. Engine temps have been climbing for decades. New materials and technologies allow higher engine temps, which increase efficiency and reduce cooling demands. Perhaps certain engines under certain conditions are exceeding what dino oils can take. It's hard to tell how close your oil is to being cooked without sending it in for regular analysis, synthetic oils give me peace of mind.

[forester2002s]

I agree with Scoobaroo. I too use the cheapest API-tested dino oil that I can find, and I change it frequently (every 3000km). That may sound excessive, but it doesn't cost me much, and it gets me under the car more frequently than otherwise (it's a Zen thing).

 

Sludge? What sludge?

[Scottbaru]

Sludge? What sludge?

If you lurk on car forums where they have sludge problems, it comes up frequently. I'm guessing Subarus haven't had much trouble with it. I know there are lots of air-cooled boxers, so maybe easy cooling is one of the advantages of boxers?

[99obw]

The NA boxers are exceptionally easy on oil, to the point that some owners seem to take for granted that oil quality doesn't matter much, and it probably doesn't for most. Other make's engines are much less forgiving of oil quality. As I mentioned earlier in this thread, I have seen significant sludge with 3k changes on cheap dino. Never seen it with Pennzoil, though Pennzoil was known for sludging many years ago. I saw a suby engine recently with some deposits, not terrible, with 5k changes with cheap dino on a long distance commuter.

 

There is some truth to most of the wear occuring immediately following an oil change. I don't understand the mechanism, but I can dig up some info if people are interested. The SAE has some papers on it IIRC.

 

Think about this:

Q. When is the worst possible oil starvation your engine normally experiences?

A. The first time you start your car following an oil change.

[cookie]

There is some support for the folks who say that changing the oil quickly is better. Then you still have more oil left on the bearings.

Over the years I have seen a number of devices that built up oil pressure to prevent dry starts. It would be interesting to see how much wear those prevent. There are racing devices that store pressure to prevent a total drop if starvation occurs.When I rebuild an engine I lube the bearings and prelube them, (spin the oil pump with a drill), before I start up the first time.

I'm not sure that I am still in the frequent dino oil change camp as I am hearing too many sludge stories. Cars like my BMW easily attain oil temps that can break down dino, which is why high performance motors come with synthetic. A few years ago I recall a story about the introduction of a new Corvette where they had to decide between the weight of an oil cooler or synthetic. Synthetic won.

I also believe that in a low performance motor like my Subaru that dino does not get challenged. In a high po WRX this might be another story.

[frag]

 

There is some truth to most of the wear occuring immediately following an oil change. I don't understand the mechanism, but I can dig up some info if people are interested. The SAE has some papers on it IIRC.

 

Think about this:

Q. When is the worst possible oil starvation your engine normally experiences?

A. The first time you start your car following an oil change.

 

I also saw those statistics (and they seem to be scientific) and can hardly understand the logic of them.

If you fill the oil filter when replacing it, starting the car aftewards produces less "oil starvation" than letting it sit overnight. But maybe the studies were made while keeping the filters empty before start up.

[cookie]

Some engines have the filter upside down. It always seems to me that this would cause more wear, but it sure is easy to change the filter. Subaru's placement of the oil pump is interesting too. Many of the engines I have worked on placed it low in the pan. The oil pump was full when you pulled the engine apart. As one of many strange Subaru designs you have to say the thing must work becuse people get 300,000 miles out of 2.2s. I think VWs had it there too if I recall correctly.

[99obw]

Over the years I have seen a number of devices that built up oil pressure to prevent dry starts. It would be interesting to see how much wear those prevent. There are racing devices that store pressure to prevent a total drop if starvation occurs.

 

http://www.amsoil.com/StoreFront/amk.aspx

 

I also saw those statistics (and they seem to be scientific) and can hardly understand the logic of them.

If you fill the oil filter when replacing it, starting the car aftewards produces less "oil starvation" than letting it sit overnight. But maybe the studies were made while keeping the filters empty before start up.

 

IIRC the reason is more related to chemistry than oil starvation. I just mention post-change starvation because it's intuitive to me as a reason not to "over-change" one's oil.

 

It would be nice if manufacturers equipped an oil change injector disable feature so crazy people like me could easily spin an engine until the oil pressure came up before actually starting it. When I used to be involved in small time dirt track racing our car had two switches related to starting. One for the coil and one for the starter. I don't remember for sure if fuel delivery was tied into the coil switch. The driver would always spin the engine a bit to pump some oil before starting. I suppose one could remove power to the fuel pump or the injectors on a modern car.

[cookie]

I would think that Amsoil device would be interesting in a taxicab.

[99obw]

I would think that Amsoil device would be interesting in a taxicab.

 

Are you thinking that the taxi's engine would never wear out if it didn't experience startup wear? Might be a very interesting test for the Amsoil device indeed.

[frag]

http://www.amsoil.com/StoreFront/amk.aspx

 

 

 

IIRC the reason is more related to chemistry than oil starvation. I just mention post-change starvation because it's intuitive to me as a reason not to "over-change" one's oil.

 

It would be nice if manufacturers equipped an oil change injector disable feature so crazy people like me could easily spin an engine until the oil pressure came up before actually starting it. When I used to be involved in small time dirt track racing our car had two switches related to starting. One for the coil and one for the starter. I don't remember for sure if fuel delivery was tied into the coil switch. The driver would always spin the engine a bit to pump some oil before starting. I suppose one could remove power to the fuel pump or the injectors on a modern car.

 

Good idea. My antitheft device disables the ignition but not the starter. So I could spin the engine a few seconds before actually starting anytime I wanted.

[slo5oh]

I just thought I would chime in here and back up cookie on his claims. I too have found the boxer to prefer something thicker than the average 30 weight with regard to piston slap and engine noise in general.

 

This is crazy... I posted a message here a week or 2 ago... here: http://www.ultimatesubaru.org/forum/showthread.php?t=33808

 

I know my '98 2.5 is a different beast, but I've found that my piston slap gets worse with thicker oil and goes away with mobil 1 5-30 wt (also gone with 0-30wt)

[Setright]

99obw just disconnect the crank angle sensor. No amount of cranking will start the engine. Of course, as Frag has thankfully pointed out already, you would have to do this EVERY morning.

 

We Sube owners are luckier than most, our oil pumps are cleverly designed so that the oil doesn't drain back into the pan, meaning quick pressure increase on start-up. (Part of the EJ22 development, and who would dis that engine??)

 

Also, our filters are bottom mount, meaning they can be primed during oil changes.

 

PLUS! Our igniton/fuel systems let the engine crank for longer if the ECU registers a low engine temperature. Thus priming the bearings. (Some BMW engines do this too, notably the V12's which can take a LONG time)