Oil type

[AirTool]

I know it seems like I'm splitting hairs, but seriously- theres a big difference between:

That's funny - Maybe its like saying "I don't disagree"

All: The biggest problem I remember with synthetic oils is elastomer compatiblity. But I think that problem's gone now. The question is: what changed? the oil or the elastomers? Because an old engine might still have old elastomers. The ones I remember to be most sensitive were valve guide seals. I also know of a guy that spilled some syn oil in the late 80's on his A/C hoses to the evap and within a week, they both swelled up and popped.

I don't see how a modern (2000+) GM engine couldn't get along w/syn oil.

[gride]

i agree. i'm pretty sure i have the same block in my 2004 yukon which i've always run synthetic in with no problems. the reasons i have not ever in my boat is b/c the manual says don't, most folks on here like rotella t, and i always change the oil in 50 hours or less(usually about 40-45).

[High altitude]

What about Royal Purple? I know it's expensive but I have always heard great things. -Marc

[gride]

all of those who say synthetic is better or royal purple is better than anything else out there, have you actually ripped anything open and examined it to see the differences in the same engine under the same conditions for the same amount of time with 2 or more different oils?

[AirTool]

What about Royal Purple? I know it's expensive but I have always heard great things. -Marc

What about it?

[High altitude]

About a million years ago (seems like that to me) we did a project in my industrial engineering class. It was a simple test on coefficients of friction and heat tolerance. Synthetic won hands down. The heat tolerance was really noticeable.

For day to day use, I don't think it matters. When you have an impeller go (happened to me for the first time last year) and your wife doesn't notice it for almost 2 minutes, you might be glad you ran the synthetic. I had no engine damage but my exhaust tubes have sprouted some micro-holes from the heat. I simply won't run anything but synthetic. I think RP is probably a waste but I decided to run some this year just to see if I get any of the fabled performance increases. -Marc

[High altitude]

What about it?

Do people recommend it? I thought there was a fairly vocal contingent who thought it was the best. -Marc

[gride]

so ya'll did a test on paper?

[AirTool]

Do people recommend it? I thought there was a fairly vocal contingent who thought it was the best. -Marc

Yes....there are many people who are infatuated with Royal Purple.

In mid 1980s, I knew a retired guy who rep'd the oil as a part time job. He called on refineries and companies and sold to consumers on the street also. He swore by it. "Best on the planet. Every other oil is crap. This stuff goes 20k miles. Awesome purple filters also available." .....all kinds of crap. I worked at the local auto parts store (high school age) and one time he laid it on me 110%. I felt sick to my stomach later thinking of how everyone else on the planet including my dad was ruining their engines by using non-purple oil.

I don't know about the oil....but man that guy was a good salesman. I suspect the company is full of them.

[gride]

i've got a line of oil coming out next year called peasant green. its vastly superior to other oils b/c of it's humble name and green color. reminds of the libtards who said black talon bullets were vest penetrators and so damaging when in actuality they are less lethal than many defense ammo made today. it was simply a pigment in the wax that made them black

[High altitude]

so ya'll did a test on paper?

It wasn't on paper. We actually did the tests. There was a simple slide test for CoF. The heat resistance was essentially the same as heating oil in a pan and determining when it gummed up.

Now, the real question is...how does that relate to performance within the engine? I don't know but it was signifigant enough for me that I have run synthetic in everything I wanted to keep since then. -Marc

[DanielC]

One of the issues regarding engine oil, in gasoline burning engines is this.
All engines use oil.
If you think your engine does not use oil, because the level on the dipstick does not drop very much between oil changes, it is because as the oil is used, the volume is being replaces by other contaminates, unburnt gasoline, water, and other combustion by products.
That is the biggest reason for regular oil changes.

Another issue affecting oil life is the oxidation in the oil base stock, from high heat. Synthetic oils do offer an advantage in this issue, but most marine engines do not normally run that hot.

Like I mentioned before one problem you have to be aware of is what type of camshaft is in the engine. Most Ford engines do not have a roller camshaft, and have to use an oil that works well with a flat tappet camshaft. Most modern engines now have roller camshafts, so most modern oils are designed for that, and do not have ingredients in them to reduce wear on a flat tappet camshaft.

[89Sncb]

Talked with white lake marine today which is the closest nautique dealer to me and they said they recommend rotella 15w-40. They said PCM has changed there recommendation on what oil was used since 2001 when the manual was printed.

[Mamigacz]

I use an oil treatment in all my engines that don't have a roller cam

Lawn mower
snowblower
classic car
ski boat

This may not be necessary with some of the synethics but its been working for me with the cheaper oils.

[TRBenj]

Talked with white lake marine today which is the closest nautique dealer to me and they said they recommend rotella 15w-40. They said PCM has changed there recommendation on what oil was used since 2001 when the manual was printed.

They are correct that the 10+ year old manual is outdated. I agree on their recommendation on the multiweight... but Im not crazy about the Rotella. They changed their formulation about 6-7 years ago when all of the increased diesel emission requirements came about. Zinc and phos were both reduced as a result... I believe 15w40 is in the 1000-1200 ppm range on both. I would say thats borderline acceptable for a flat tappet engine... Id opt for VR1 or M1 15w50, as both have 1200/1300.