0w40 synthetic oil

Discussion in 'Small Block Tech' started by Mark Demko, Sep 23, 2019.

  1. Jim Nichols

    Jim Nichols Well-Known Member

    Plus Fuel Injection. No carburetor choke to wash down the cylinders. Better oil too. I wish we had higher octane gas.
     
  2. Mart

    Mart Gold level member

    I don't have any choke.:D
     
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  3. Mark Demko

    Mark Demko Well-Known Member

    Me neither
     
  4. 70skylark350

    70skylark350 Jesus loves you unconditionally

    somehow my mechanics brain will not allow me to put 0w anything in a motor...... Guess you need an engineering brain to accept this new oil????
     
  5. Fox's Den

    Fox's Den 355Xrs

    That is the opposite there 4 qts of 10-30 and 2 qts of 15-50 Mobile 1 for me.

    Choke? what the heck is that! I have a double pumper Holley that acts like fuel injection.

    Matter of fact, the car starts faster than my fuel injected Toyota.
     
  6. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    Not true. When cold the computer richens the mixture to accomplish the same thing as a closed choke.
     
  7. UNDERDOG350

    UNDERDOG350 350 Buick purestock racer

    But it's more controlled than a choke.
     
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  8. gsgtx

    gsgtx Silver Level contributor

    its the other way around. its a 30 weight oil but flows like a 5 weight when cold
     
  9. Gary Bohannon

    Gary Bohannon Well-Known Member

    The low number is for cold temp specs.
    The high number is for hot temps specs.
     
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  10. Jim Nichols

    Jim Nichols Well-Known Member

    Manual chokes people forget and automatic(electric and hot air) stick and fail. Computer cold enrichment is a lot more accurate.
     
  11. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    The computer should be more accurate in theory but the condition is still there on a cold start. Manual chokes are a wild card for sure but a properly adjusted and maintained auto choke works pretty well as long as the driver knows how to use it.

    Anyone who has worked on an early gm efi who is familiar with the CTS failures will tell you when the computer reads -45° engine temp it'll richen the injectors up so much it'll roll coal and foul the plugs in a matter of minutes.
     
  12. Fox's Den

    Fox's Den 355Xrs

    If you set that choke correctly the car will fire right up, pull the choke back to 1/8 open with vac to keep the engine from flooding and the rpm will be at 1200. Worked for plenty of years before computers and would fire right up at 10 below 0
     
  13. Mark Demko

    Mark Demko Well-Known Member

    I was at Walmart Saturday morn. to get toilet paper, I went to automotive to check out the 0w-40 Mobile 1, it went up 3 bucks for the 5 quarts:mad:
     
  14. OddfireV6

    OddfireV6 Active Member

    SAE 30w does not equal SAE 30. The "w" does not mean weight. It means winter. Oils with a "w" following their viscosity grade are always lower viscosity than oils of the same grade without the "w".

    It comes from the days of the seasonal oil change where you ran a SAE 20 oil in summer and a SAE 20w oil in winter. The 30w was lower viscosity. You had "summer grades" (SAE 10, SAE 20, SAE 30) and "winter grades" (SAE 10w, SAE 20w, SAE 30w). You picked your winter oil based on how cold your winters were and you picked your summer oil based on how hot your summers were. Extreme climates used SAE 30/10w. Mild climates used SAE 10/30w.

    Multi-viscosity oils were marketed as "year-round" and "all climate" oils when they first came out. SAE 10w30 equals SAE 10W at 0 degrees Fahrenheit, but also equals SAE 30 at 212 degrees Fahrenheit. Hence why it could be used year-round in almost any climate: it had the same viscosity during a cold start in January at 0 degrees Fahrenheit oil temp as SAE 10w, but also had the same viscosity during a hard drive in July at 212 degrees Fahrenheit oil temp as SAE 30.

    It's hard to understand how modern multi-viscosity oils work without first knowing how the old summer grade and winter grade single viscosity oils worked.

    Keep the transition temperature in mind. SAE 30 single viscosity summer oil is a viscosity of 30 at 212 degrees Fahrenheit. Any colder than that and it will have a higher viscosity....40...50...or more. SAE 0w30 is also a viscosity of 30 at 212 degrees, but most engines do not run their oil that hot. At a more reasonable 170 degrees, the 0w30 may only have a viscosity of 20. Therefore, the SAE 30 single viscosity oil has a higher viscosity than the 0w30 at the normal operating oil temperature of the engine. Keep in mind that is also the average oil temperature in the oil pan. Some areas of the engine create localized heating or cooling of the oil that will cause the viscosity on those areas to change.
     
  15. gstewart

    gstewart Well-Known Member

    A while back, I was looking for a can of 10W30 oil and guess what? no could find. Lots of 5W30 & 0W30.
     
  16. buicksstage1

    buicksstage1 Well-Known Member

    Selecting should not be a guessing game or by the seat of your pants. When I did my Auto Mechanic's in the 80's I was taught that bearing clearances and nothing else.
    Oil choice should be by bearing clearances, it's been like this for as far back as I can remember. Regardless what type of bearings are used in an engine, clearances have to be precise and correct for the oil viscosity that will be used to lubricate the motor: Thin, low-viscosity motor oils require tighter bearing clearances than heavier-viscosity racing oils such as 20W-50, straight 40 or 50 weight oils.

    Some recommended bearing oil clearances for various oil viscosities:

    .0015 to .0018 for 0W20 or 5W-20

    .002 to .0024 for 5W-30 or 10W30

    .0025 to .0029 for 10W-40 or 15W40

    .0030 to .004 for 15W-50 or 20W-50

    For main bearings:

    .0015 to .002 for 0W20 or 5W20

    .002 to .0025 for 5W-30 or 10W30

    .0026 to .003 for 10W-40 or 15W40

    .0031 to .0041 for 15W-50 or 20W-50
     
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  17. sean Buick 76

    sean Buick 76 Buick Nut

  18. UNDERDOG350

    UNDERDOG350 350 Buick purestock racer

    Is there a source for this information or personal experience? Not disagreeing, looks solid.
    Does this also apply to diesels as they always seem to use thick oil.
     
  19. TrunkMonkey

    TrunkMonkey Well-Known Member

    Cummins are about .002 -.005 on the mains and typically 5w-40 is recommended.

    Bearing oil clearances and oils are going to be typical across the board as the physics are the same regardless of the source of power used to run the engine.

    And the use of the engine is also pretty much the same for adjustment in clearances, RPM range, "normal operating RPM", max RPM and load over time, and type of fuel and induction, as well as all the other variables and the nuances of the actual engine.

    No one size fits all, but the "general rules" of mekkanix apply to all things that suck, squeeze, bang, blow.
     
  20. buicksstage1

    buicksstage1 Well-Known Member

    Those spec's are right from Lake Speed jr at Driven oils and are almost exactly the same as what I have lived by for decades. If you search their site they rate their oils by bearing clearance. I can't stress the importance of the oil wedge enough, you do not pick oils by desired oil pressure. Idle pressure is controlled by main bearing oil clearance and pump efficiency. OP at rpm is controlled by bypass spring pressure. The diesels are a different animal but our BBB's have a huge main journal and it gets fed before the rods do hence why I groove the main saddles adding 2 more oil feeds that carry the wedge further which also increases the oil to the rod bearings by 80%+ on any BBB that gets a deep oil pan.
     

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