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Thread: Engine Oil

  1. #1
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    Engine Oil

    I have a 2008 Shelby GT 500 The owners book says to use 5-50 w oil. Can I use 20-50 instead with out damage? Royal Purple doesn't seam to have 5-50 oil. Any help?

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    Re: Engine Oil

    Big NO!!!

    A 20W-50 oil is more for "racing" old style and not recommended for the tight tolerances of these "newer" style engines.

    Go to the dealer or search the net and find the right stuff. It may cost more put don't go cheap on the vehicle.

    Tom

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    Wink Re: Engine Oil

    if you prefer mobil 1, 5w-50, you have one choice according to mobil1 management. if you have a mobil 1 distributors in your area(big blue storage tanks) they also sell to public. for those of you in the metroplex area, i purchased mines in Ft. Worth, reeder dist, wilbarger st. (817-429-5957) paid $5.60 qt. only sold in 12 packs. dealers have a syn, $9.60 qt, don't think it's mobil 1.
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    Re: Engine Oil

    Quote Originally Posted by Archie View Post
    I have a 2008 Shelby GT 500 The owners book says to use 5-50 w oil. Can I use 20-50 instead with out damage? Royal Purple doesn't seam to have 5-50 oil. Any help?
    Hi Archie from Wylie in lone oak texas. No matter if your car is still in warranty or not use what the book says, 5w 50. It has a spec number ending with a B. Ford motorcraft makes it and Valvoline roush makes it. You can buy the valvoline on line from roushperformance.com and the ford at kmansparts.com. What part of texas are you in?

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    Re: Engine Oil

    Archie,,be careful and read the literature on these 5w 50 synthetic oils. Mobil 1 and Castrol make the 5w 50 synthetic but they have not gone thru the test to make the B spec for the shelby gt500. Only the ford and valvoline state that they meet the ford B spec.

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    Re: Engine Oil

    spec B oil rating is nothing but a wider viscosity ( Gap) rated oil. owners manual says 5w-50, not ford 5w-50.
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    Re: Engine Oil

    Quote Originally Posted by firetruck View Post
    spec B oil rating is nothing but a wider viscosity ( Gap) rated oil. owners manual says 5w-50, not ford 5w-50.
    The owners manual says 5w 50 that meets Ford spec WSS-M2C931-B. I did find on line where Castrol 5w-50 says in writing that it meets that Ford spec. and you will also find it in writing for the Ford Motorcraft and the Valvoline Roush oils. This is not me talking, it is the manufacturer's on line PDF files. Ford Motorcraft, Valvoline and Castrol alll say that they meet the WSS-M2C931-B spec for the GT500. Mobil1's PDF does NOT. Now you want to bet your 18 thousand dollar engine, go right ahead. Synthetic oil is man made and it has DNA and Ford labs can dissect what oil you have used in your car and tell you exactly what it is. If your engine were to fail and Ford says show us where Mobil 1 meets the spec in writing and you can't guess what they are gonna say. Should have read th book.

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    Question Re: Engine Oil

    I think before you get cross-haired, tell us form members what a spec B oil is. until you do this , you're sucking up to ford. the only reason ford is asking for this weight oil, is because it is a blown engine ( higher loads on parts). in the interest of fact, tell me what this oil can do that mobil 1 5w-50 can't. please school me.?
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  9. #9
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    Re: Engine Oil

    There is a WSS-M2C931-A spec oil and a WSS-M2C931-B spec oil. Ford motor co says to use the B in the GT500 per the owners manual. I mentioned 3 oils that meet this spec and they say so in writing. Valvoline and Castrol are made by their names. The Ford motorcraft oil is made and bottled by Conoco so I am not sucking up to Ford. What Mobil 1 cannot do is make a statement in writing that their oil meets these specs for use in the GT 500 and until they do I will consider them a NO NO in my Shelby. As for schooling I cannot make you read the owners manual and compare that to the 4 manufacturer's literature on their oil. Three of them make a statment in writing and one does not. It seems to me that you are the one sucking up to Mobil1. No hard feelings, please. I just read the book and all the literature. I have no idea what the difference in the oils are so I have to go with what is written down.

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    Cool Re: Engine Oil

    okay let's just disagree for now. might try castrol since it's a spec B oil, but $10 a quart is ripping.
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  11. #11
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    Re: Engine Oil

    OK You might call Grand Prairie Ford and see what the Valvoline Roush is going for there. I think it is around 8 dollars but call to see if they have it in stock.

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    Re: Engine Oil

    okay here is the skinney on the confusing spec-B oil.
    wss-m2c931-B. is nothing but a part number for the oil, ford does shit like that. the 2008-2009 have the A. in a nut shell, all this means is that the new oil is now rated (SM) the same as mobil 1 5w-50. conoco makes it for ford, valvoline and mobile make are them.

    use any oil you want, as long as it's a 5w-50 full synthetic, rated (api-SM)
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    Re: Engine Oil

    I already said OK. I used printed literature from each of the oil manufacturer's as a source of my information. What is the source of your "skinney" please.

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    Re: Engine Oil

    talked to several service managers. as far as they were concerned, and they checked. this is a part number, rather than a grade. to avoid any problems i went with the ford (conoco)stuff

    if valvoline (roush stuff) becomes available at a lower price, i will use it. i will continue to research this issue.
    2010 shelby cobra mustang
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  15. #15
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    Re: Engine Oil

    I used Mobil 1 in my dodge PU for years and it did seem to get better gas mileage. I was very disappointed when I got my 500 in Feb and could not find where they met that spec number and letter. Greenville ford was not even aware that the shelby used 5w 50 oil when I called them so I ended up ordering the valvoline on line. I sure hope archie benefits from all this. He started it.

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