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Thread: Oil ?

  1. #1
    Taylorman
    Ive read before of some people saying that with synthetic oil you don't get the pressure drop when the oil gets hot like with conventional oil. Is this true and if so, what brand oil is everyone running that has cured the pressure drop. Im seeing a pretty substantial pressure drop from hot to cold.

  2. #2
    Beer-30
    I haven't specifically "tested" that. I seem to get the same variation between hot and cold that I did with conventional. Liquids are just going to get thinner with heat. Any heat. I ran the boat for the first time yesterday with Mobil-1 10-30 in it. Fully warmed up, I saw about 22 at idle and 45 under way. Plenty (stock 496HO). Didn't really pay attention to the previous readings. Sorry.
    My pickup (7400 Vortec) with the same Mobil-1 starts off almost pegging the 80 lb gauge at cruise, then settles to 60 after warmed up. Idles at 40 cold, then about 25-30 warmed up.
    Generally, tests show that there is a 10-20 degree drop in warm temps with a switch to syn. This would account for slightly higher pressure(s) than before since they don't get as warm. Hope this helps.

  3. #3
    HammerDown
    WHICH OIL?
    Question: I changed the oil to Mobil 1 10W-40 synthetic because I felt it offered better protection when sitting for extended periods and start up. Lately I saw an article that said these oils are not recommended for marine use due to lack of shear strength at wide-open throttle or high temperatures associated with marine engines. I usually run at 3,000-3,200 rpm. Do I need special marine oil? Also, what about Delo 400 15W-40 oil as a possible alternative?
    (name removed)
    Answer: from Mr. Bob Teague...There are a lot of good synthetic oils out there for most automotive and some racing applications. But it is commonly felt that *petroleum-based straight-grade oils are more desirable for marine engines*. Marine engines tend to contaminate oil more quickly than automotive engines. This is because of the presence of moisture and a tendency to have more fuel contamination in the crankcase. The problem is related to the effect of the additive package than the base oil itself. Multiviscosity oils that rely on chemical reaction to simulate a more viscous oil when hot can lose their ability to perform well, and may get too thin for the extreme loads and elevated temperatures.
    I recommend using a good quality straight grade engine oil, either SAE 30 or 40 depending on the climate and what clearances exist in your engine. If you notice that the oil pressure drops quite a bit while idling after the engine is hot, select a heavier weight oil.
    So there ya have it.
    ALSO...
    And another Question to Mr. Bob Teague about Synthetics in Boats>>>
    WHAT ABOUT SYNTHETIC OIL?
    Question: I would like to know if it is okay to run synthetic oil in a boat engine? I have read many different answers to this question, but would appreciate your professional opinion. I am running a stock 502 Magnum MPI and have always used Mercury's oil in it. I use Valvoline SynPower synthetic in my tow vehicle, but don't want to put synthetic oil in my boat without knowing if it is okay. If it is okay, what brand do you recommend?
    (name removed)
    Answer: This is a widely debated topic. Of course, the synthetic oil manufacturers would want you to believe that their products are going to increase your engine life. I have used a few synthetic oils with pretty good success, including Red Line, Mobil 1, and Amsoil to name a few.
    In racing applications, I have done testing by using two different types of oil in each engine in the same boat. After the race, when the engine was disassembled, there was evidence that the synthetic oil was slightly superior in the competition environment. The same results have not been observed in the recreational marine engines, though.
    More recently, I have noticed that engines with roller lifters used in the pleasure-boat environment have exhibited undesirable wear patterns when synthetic oil is used. Specifically, because the oil is more "slippery," it appears that the rollers are sliding on the cam instead of rolling. This results in flat spots on the rollers and increased wear on the cam lobe. This problem only seems to present itself with lower valve-spring tension applications typically used with hydraulic roller cams. In race applications, with solid roller setups where 250 or more pounds of spring pressure exists when the valve is on the seat, there seems to be enough pressure to keep the roller on the lifter rolling on the cam instead of sliding.
    Depending on your climate and the water temperature you typically operate your boat in, the viscosity of your oil should be selected accordingly. I believe that a straight grade SAE 40 oil is the most suitable for the majority of the performance marine engines. SAE 30 would be better for cooler climates. For extreme performance and supercharged engines, SAE 50 is suggested. Most synthetics are a multi-viscosity oil. Fuel dilution of the oil and contamination as a result of increased moisture in the crankcase seems to affect the multi-viscosity oils faster.
    The most important thing is that you change your engine oil regularly and use a good quality oil. I think an oil change every 25 to 50 hours is a good idea. The higher performance your engine is, the more often the oil and filter should be changed. I use Kendall SAE 40 in all the pleasure boats in our Southern California
    **********************************************
    Whooow, did he say "Kendall" :wink:
    Actually, I always ran Kendall GT in all my engines... Harley, Vette, Jet Boat. But unfortunately this season it's no longer available in my area. :cry:
    I just started using Valvoline 50/wt Racing blend

  4. #4
    BK
    I used to use the Kendal GT 20/50 but havent since the "color change". I ran Valvoline VR1 20/50 the last few seasons with good results and this year im using Mobile 1 15/50. With the mobile one I notice about a 10lb pressure increase and it doesnt drop off nearly as much after the motor gets hot, so im kinda sold so far on the Mobile 1.

  5. #5
    Beer-30
    My whole family has been running Mobil-1 in all our late model (1998 oldest) GM vehicles. All have roller cams. None have ever flat spotted. Mine is going on 70K miles with synthetic for 60 of that. I am not saying it can't happen, but I haven't seen it.
    Additionally, Corvettes come stock with it. Also, I belive SLP has always put it in Firehawks and Camaro SS. I know Reeves Calloway used it in his modified vettes as well as twin turbo. All have hydraulic rollers.
    My truck goes down the highway at 2700-3200 depending on speed. I cruise the boat at 3500 or so. Kinda the same thing. Also, the 496 bottom end is quite similar to the 8.1 pickup / motorhome motor. It doesn't really know its in a boat. My opinion.

  6. #6
    Boater Bill
    Have you tried Lucas Oil Stabilizer with your conventional oil???

  7. #7
    Squirtin Thunder
    I used to use the Kendal GT 20/50 but havent since the "color change". I ran Valvoline VR1 20/50 the last few seasons with good results and this year im using Mobile 1 15/50. With the mobile one I notice about a 10lb pressure increase and it doesnt drop off nearly as much after the motor gets hot, so im kinda sold so far on the Mobile 1.
    Personally I found the new VR1 20w-50 to not hold up to all the stresses that I put on it. Now I kinda freak when I see a 5psi drop. After searching the Valvoline web site, I found that the VR1 is nothing more than reg syn oil with friction modifiers. Now if you remember the Valvoline Racing of 10 years ago here is the answer Valvoline pn# 851 (20w-50), give it a try !!!
    Jim

  8. #8
    Ol Yeller
    I use Mobile1 15w50. This stuff is slippery as snot and stays very clean on the stick.

  9. #9
    Squirtin Thunder
    I use Mobile1 15w50. This stuff is slippery as snot and stays very clean on the stick.
    If it stays clean there is a problem. One of oils jobs is to clean.
    Or is it non-detergent ???

  10. #10
    Lake Ape
    S. Thunder, you get my PM? That lady thinks I'm a bible salesman or something! I like Royal Purple, hell I went halfsies on a 55 gallon drum of the stuff, run it in my car and truck!

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