Mobil 1 vs Valvoline's racing oil data point

[IdahoDoug]

My 7.4L V8 in the boat calls for straight 40 wt heavy duty oil in my climate. I've used Mobil 1 for years instead, with the latest couple changes being with Mobil 1 0-40. Last year, I couldn't find the M1 so I used a highly recommended top shelf Valvoline 40wt racing oil - specifically designed for high RPM high temp, high horsepower applications.

My app certainly fits as the engine puts out 330hp at the prop, so it's probably 350hp at the crank. Plus, this same engine in a Suburban turns 2300rpm at freeway speeds, but at my most economical cruise speed mine's turning 3500 and at fast cruise it's turning 4000rpm. For sometimes an hour. Wide open is 4400rpm - major revving and the reason it gets 2.35mpg at economical cruise.

Anyhow, I use a dipstick suction pump to remove the oil as there's no other way. When I took out the high fallutin' Valvoline today it was shot. So thick the pump had a LOT of trouble getting it out despite my usual anal technique of only changing this engine when it's hot. Looked like black pudding and I can't even get it to slosh in the can, so something about it has broken down badly.

Felt good to refill it with Mobil 1 synthetic, which has come back out every time looking like dirty oil but flowing properly. Makes that $5/qt seem like a bargain if it's going to keep my boat engine properly lubed when I'm running hard.

Since I use the exact oil in the 80s, it's also nice to have a few spares for big trips that cover both vehicles...

DougM

 

[sixsracing]

I have run independent tests on dino motor oil. Valvoline was one of the worst for pressure and cleanliness. Castrol came out on top every time. Followed by Kendall. I did not test synthetics because at that time I changed my oil every one thousand miles and didn't see the need for synth. oil.

 

[cruiserdan]

I use Mercury Marine 25w-40 in my I/O

 

[IdahoDoug]

Dan,

What's the rattle/qt on that stuff? According to the manual, a 20-40 is a slightly less desireable choice but I'd do it if need be. What's your thinking on the Merc stuff vs Mobil 1. I figure a 0 wt at startup is OK as long as I don't put the engine above idle until the temp gauge is showing warm (though my experience is that oil temp comes up AFTER water temp by quite a margin). It has always been my practice with marine engines to wait several minutes before loading it such as getting up on a plane.

DougM

 

[cruiserdan]

I don't remember the cost but it is less than synthetic. Mercury recommends the 25w-40 and my boat dealer, who is a very sharp fellow, really likes the stuff so I went with his recommendation. He also runs it in his truck that he uses to pull the big boats with. 25w-40 is an odd-ball viscosity, I have not seen it in automotive oils just marine oil. I do not know who blends it for Mercury. I have run 20w-50 Valvoline before but it looked fine to me when it came out and the observed oil pressures were compreable to the 25w-40 Merc oil. My engine is a 4.3 LX with a roller cam and a 4bbl carburetor. I run it about 20-25 hours a year.

 

[IdahoDoug]

Thanks, I'll look into that for next year as I'm a little leery of the cold engine protection factor. As I say, this can be accounted for by not loading the engine, but OTOH it's an open cooling system and some of these deep NW lakes or the Puget sound (47 degrees year round) may provide more cooling then I need.

We put up to 100 hours a year on our oil, and sometimes run it pretty hard. A few years ago we ran the entire Hood Canal on the Puget Sound round trip from Port Townsend in an afternoon. It was millpond flat and I ran a steady 50 mph (WOT is 63) the entire time - some 4 hours of steady running around 4000 rpm. That was on Mobil 1 and I was confident in the engine's condition as a result, but clearly this engine's oil choice is the most critical of any engine I've ever owned because of its capability.

I'll check into the Merc stuff. Heck, they already require me to use a Merc synthetic outdrive oil in the Bravo III (counter rotating dual props) when I'm itching to use Mobil 1 so maybe a Merc clean sweep is in order. A Merc tech talked me out of it by patiently explaining that there are some unusual bushing materials here and there in the outdrive that are no longer used in the automotive world, so the latest automotive lubes don't comprehend them. Seemed plausible and the opinion was given in the spirit of real world info, so I accepted it at face value.

DougM

 

[cary]

Just a note. Race oils like the Valvoline race traditionally have less antioxidants to help prevent pinging (I don't know why it works that way but it does). Accordingly, they don't hold up for very long in real world use. Also, Valvoline has not been doing so well with their UOA's on bobistheoilguy.

Cary

 

[reffug]

Once again, and as has been consistent on this board then M1 is the clear cut winner as far as longevity and engine protection goes no matter what the application. 5$ doesn't seem all that much to me for the peace of mind the product provides. Which reminds me time to get some BG44K.

 

[cary]

For 99.9% of applications Mobil 1 seems to work best. People keep trying to find other brands that work better, but M1 really has the quality end of the market covered and at a decent price.

 

[IdahoDoug]

Yeah, agree. I'm feeling much better now about those upcoming occasional high spirited top speed runs with an American V8 running at 4400 (yowza) for several minutes at a time. Had I known what the oil was turning into last summer, I'd have dumped it ASAP.

 

[cary]

Doug,

You may want to short interval this change in the boat to help get the crude out left by the valvoline. It shouldn't be a problem, but I bet there was some oil left after you suctioned it out.

Also, you mention that the motor runs cool because of the cold lake water. Have you considered trying a flow restrictor in the thermostat housing? It would slow down the coolant flow and allow the motor to get to operating temperature, where everthing will work better.

Cary

P.S.- The only thing better than a BB in boat is a BLOWN BB in the boat. We need some pictures of that rat with a 6-71 sitting on top.

 

[IdahoDoug]

I'll look into a flow restrictor. It's about time to replace things like the impeller that brings in raw water, and a thermostat so I'll check into it.

Yeah, a blown EFI 7.4 would really blast. I'm overpowered (a misnomer, I grant you) already though. The coast guard plate says 300hp max and I special ordered one with EFI and it arrived with 330 hp at the prop. Dunno how that happened, but the thing really rocks and it's sneaky-silent in the true sleeper idiom. Looks like the slightly bloated puffy cuddy cabin boats every family has. When an open exhaust go-fast whizzes by I like to lean into the throttle until I'm pacing them. This irritates them, so naturally they hit the throttle. So do I. Turns out very few of those boats will top 60, and only the REALLY built ones (Hallets, Velocity, etc) made for racing get much over 65. So if I'm lightly loaded and hang with them at 65 with a couple kids lounging on the sunpad and a pair of bicycles on the swim platform, they just about go apopleptic. I try to be casual about it, but I've broken three nice 8 foot marine band antennas doing that, so now I have to reach out and lower it before the truly high speed runs. Fun stuff.

DougM

 

[cary]

65!!!! That's really good. No need for a blower.

 

[IdahoDoug]

Yeah, that's really moving on the water. If I hadn't ordered it with the heavy twin prop Bravo III outdrive I'd probably see another 3-5mph but this is way fast enough and I love the outdrive - wouldn't have it any other way. Ideal efficient cruise speed (2.45 MPG) is right around 45mph. Passes anything but a gas station.

DougM

 

[cruiserdan]

No tendency to "Chine-walk" at that speed?

 

[IdahoDoug]

Dan,

You know your stuff. When the boat was new, I found it leaned to one side. Did some quick research with folks who build boats (ScottM's buddy) and found that builders put a slight "hook" on the rear edge of the bottom to counter torque lean (all outdrive props go the same direction unless you've got twins). Suspecting that the newness of the BIII outdrive meant my builder didn't have a separate mold without this 'hook" (slight downward flare), I called and spoke with the owner. He owned up to it immediately. So at his expense, a local boat company removed the hook and also tuned the rear edges to his liking (has go fast experience). Don't get me wrong, I've felt it chine walk a couple cycles with just the right waves at absolute full throttle, but I like that it stops itself rather than continuing - indicating things are well with the angles and surfaces below.

As a result, the boat has superb high speed manners. Naturally at high speeds, I trim the nose high, and the twin props have tremendous grip so it's quite stable. THEN (you knew there'd be more to this story, eh?) a few months after I bought it (new), the pinion bolt on the outdrive gear simply loosened and fell off. 5 seconds of food blendering between hardened forged gears and the entire outdrive was toast. MerCruiser air freighted a new outdrive (was a known issue) to the dealership under warranty and I asked them to take extra care to align the outdrive and since they knew about the special order engine they carefully aligned it to ensure it is in the right spot relative to the X dimension.

So, I ended up with a hot rod family tub that's been carefully tuned and aligned by experienced guys at no cost to me. I was impressed with both MerCruiser and Rinker and yakked this up across all the boat forums. Really top notch responses by both and the boat's been trouble free in the ensuing 450hrs.

DougM

 

[cruiserdan]

My dealer was a hot-rodder too and part of what he did was re-gear all his drives for high altitude and he re-worked the stern/transom area of the hulls to get the boats to plane faster (Chaparral boats). He warned me to keep mine below 55mph to keep it from chine walking. It'a 19 foot bow rider and 52-53 is plenty fast in it.

 

[reffug]

No tendency to "Chine-walk" at that speed?

Pardon a non-boaters ignorance but WTH is 'chine-walk'?????

 

[cruiserdan]

Chine walk is basicly a high speed instability. What happens is the hull starts to rock side-to-side and the boat can change direction very violently. It can be very dangerous.

 

[IdahoDoug]

It tends to happen at higher speeds because the boat gets higher and higher out of the water as it goes faster. At some point, the horizontal plane of the hull's resistance and the horizontal plane of the prop's thrust get so close that things get unstable. Kinda like if you've ever seen one of those cement or tar trailers banging from side to side as it's towed down the street, and also why trailers tend to get out of control while going downhill.

DougM