Snake Oil doubter

[FB71]

Ok, I'm not one to believe every flash-in-the-pan miracle product. I have even doubted some synthetic oils' qualities. However, I'm going to give synthetic oil an opportunity to prove itself to me, specifically, AmsOil. I bought several quarts of 5w-30 to use in Fester's rebuilt heart, and I'm curious to see what potential effects it may have fuel economy, durability, etc. DarkDan, I have to say, you have provided significant evidence to cause me to re-evalute my positions against most synthetics. Any words of wisdom for me as I embark upon this adventure?

[qaking]

ops: Don't drink your AMSOIL thru a straw....

[89fester]

Synthetic is no snake oil. I believe the aircraft industry has been using synthetics for 30 plus years.

You usually don't want to switch to it on a very high mileage engine, unless you want to find all the gaskets that are borderline leaking.

You also do not want to break in a new engine using synthetic, because I have heard the rings will not seat properly. You usually switch to it after the first or second oil change.

89 L

[FB71]

I don't doubt synthetic oil. I know its a good product. I worked on aircraft in the Air Force. I'm just doubtful that automotive grade synthetics live up to the marketers' claims. I can't see how synthetic oil would adversly affect break-in, since many manufacturers use Mobil1 and other synthetics as new-fill right from the engine plant. AMG and the Mustang Cobra use Mobil1 as new fill, along with ChromeMoly rings, and they have no trouble seating. I'm doubtful of fuel economy gains and extended drain intervals claimed by the synth oil manufacturers. That's what I'll be evaluating.

[Silv3rBull3t]

Well you are correct, much more precisely built engines (cars for that matter) can be broken in with synthetic but I wouldn't use it for a Festiva/Mazda engine from the early 90's... -Kyle

[89fester]

Well you are correct, much more precisely built engines (cars for that matter) can be broken in with synthetic but I wouldn't use it for a Festiva/Mazda engine from the early 90's... -Kyle

Yes, most newer cars come with a specific break in oil, depends on the manu./brand. And I'd go with what you said, an '06 Carrera 911 motor is a little more precise than an old POS Festiva engine.

You still at VA Tech? I was on the Formula SAE team in the early 90's. Haven't kept up with what they are doing the last few years.

89 L

[EVOGUN]

I think the factory rings on the B3 are chrome. So yes synthetic bad for break in. The finish on the cylinders and the ring material would be a major thing whether you can use synthetic for break in or not.

I use AMS oil 0W-30 and its been good to me and my customers.

Thanks :wink:

[FB71]

ok, for break-in, I'm sticking with AMS. I've built, rebuilt, and repaired many Cobra engines in my day. When I compare the piston to cylinder clearance tolerances between the Romeo 4.6L 32v Cobra engine and the old Festy engines, they share the same amount of clearance. The Cobra block uses high nickel content cylinder liners and the Festy blocks have a significant nickel content as well (Austrailian iron ore). Both engines use ChromeMoly rings rings on the top compression ring, cast iron rings for the second. The piston's thermal expansion rate has no significant impact on ring seating, and the Festiva pistons are realatively stout as is.

Again, I'm not questioning usage of synthetics.

I'm questioning wether or not I should expect to see any significant gains in fuel economy, and if extended drain intervals are feasable.

[ericsmith32]

I've never seen any difference in mpg. The only observation was a faster rev. I do slightly longer oci's with synthetic since it tends to keep it a little cleaner. I do 6k oci's I could probably do 7.5-8k oci's but i'm a tinker-holic and don't mind changing a little earlier.

[darkdan]

Don't use synthetic until the break-in is over.

#1 Go look at the corvette forums to see how bad their oil consumption is. The same with lots of MB.

#2 Cylinder glazing is rare, but it can happen. On newly moderned machined engines it's rare, but not sure about rebuilds.

#3 Gas mileage difference is usually about 1% to 5%. Usually 2% in the real world. Most people don't keep accurate enough records to notice it.

#4 My aspire with 147k miles on was going 8,000 miles between changes. This time I might try to hit 12k. Not bad for a motor with a 3.6 quart sump.

[FB71]

got it.

so i'll do break-in with a conventional 5w-30

I should not expect to see a noticable increase in fuel economy.

and I should SAFELY? be able to go 8k-10k miles between changes?

[EVOGUN]

You don't have to change your oil, till you start to lose viscosity. If you want, just have the oil lab checked. That way you could go 12k no problem.

You will be surprised at the high viscosity levels even at 12K. This is the best way to know when its time to change your oil.

Make sure you use a good filter that made for high k oil changes. You could also change 1 filters(every 5-6K).

Thanks :wink:

[darkdan]

I'd run the first 10k miles on conventional oil personally.

Yes. If you're uncomfortable with that, then do a filter change and top-off about halfway through.

This will provide a clean filter and about 1/2 quart of fresh oil to bump up the TBN and additive levels.

I'm going 12k miles on this filter/oil combo this time. Unless I decide to drain it out early and do another auto-rx treatment. I "think" I have a rear-main seal leak. No drips in my driveway, but between the engine and transmission had oil on it and I'm using about a quart every 2000 miles now.

[FB71]

that's what I had planned. Replace the filter and top off every 5k, full change at 10k. I also expanded the oil sump to 5 qts (3.9qts just always bugged me) so I might change the intervals to 6k and 12k. I drive 200miles a day, so that would save me some maintainence time.