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Oil weights

Discussion in 'General Mustang Discussion' started by RagTop, Apr 2, 2017.

  1. RagTop

    RagTop Old Grumpy

    Since I moved to the Sierra foothills almost five years ago, my Mustang has been struggling with the summer 100*+ temperatures. I have 50K miles on the rebuild and have been using Castrol 10W-30. It's beginning to show the effects of a three speed automatic and lower rear end gears (lots more rpms per mile). I am considering going to a heavier weight oil but am torn between the Castrol 10W-40 semi-synthetic or the Castrol 20W-50. I used the 20W-50 for years in a first generation Mazda RX7 I owned, and managed to avoid the dreaded apex seal failures so common in rotary engines. I doubt that the car would be seeing extremely low temps around here, so the 20W wouldn't be a problem. My rebuild included a high volume oil pump and, when the temperatures are around 70* with the 10W-30 it runs with the oil pressure gauge at about 7/8 gauge. When the weather heats up, the car runs with the oil pressure gauge registering between half and 1/3 depending on rpm, showing the effects of the heat on viscosity. I don't want to cause problems for the engine with excessive oil pressure either. Any advice would be gratefully accepted.
  2. Starfury

    Starfury Active Member

    If you're concerned about oil pressure, you really need to get an actual gauge on it. The factory gauge isn't telling you anything, really. "between half and 1/3" isn't a pressure.

    Also, if you're running a flat tappet cam, I would strongly consider a high-zinc oil. I run Valvoline VR-1 in my 331, which comes in 10W-30 and 20W-50 flavors. Mobile 1 15W-50 is also high-zinc.
  3. RagTop

    RagTop Old Grumpy

    I revisited a previous post that I wrote on the same subject and took the advice of an old friend, Jeff Tepper, and ordered a case of Kendall 20W-50. My engine is flat tappet and should benefit from the higher zinc levels in Kendall. Thanks for the reply.
    Last edited: Apr 4, 2017
  4. zray

    zray who said Beer ?

    I've had nothing but great results from using Mobil 1 15w-50. Plenty of Zinc / phosphorus too.

    Tubbster1966 and Patrick Stapler like this.
  5. c6fastback

    c6fastback Member

    I ran 20w50 for many years when I lived in Placerville and Sacramento . Dark blue car , black interior and no a/c was not fun after the car was parked all day .
  6. sportsroof69

    sportsroof69 STREET CAR

    I always run 20W50 VR1 in mine.
  7. RagTop

    RagTop Old Grumpy

    I have to share this story about WalMart. My knees and shoulders have gotten so bad that I really can't change my own oil anymore. I received a case of Kendall 20W-50 from Amazon and decided to pay WalMart the $10 plus the price of a filter to install the oil. How "technical" can that be? I arrive at the auto center with my '69 convertible and the kid who is receiving asks what engine it has in it. I say it's a 302 and that non-metric information doesn't compute on his hand held terminal. He asks if it's a 5.0L and I say yes, I suppose it is. I tell him I want to purchase a Motorcraft FL1A oil filter and he looks up the proper application for my "5.0L" and tells me that the FL1A is not the correct filter for my car. I tell him that every 231, 260, 289, 302 and 351W Ford engine has always used the FL1A filter and he says his hand held says it should be an F20. He finally defers to an old guy in the lube room and comes back and says that, despite company policy, he'll be able to install the FL1A in the car. We go inside the store and he picks the last FL1A off the shelf. Now I do some light shopping and sit and watch part of "Beauty and The Beast" on their little flat screen in the waiting room and the kid who greeted me initially comes to the door and says the guy doing my oil change wants to talk to me. Odd, but OK. The second kid tells me he can't do my oil change due to company policy. He has found that I have an oversized drain plug on the car and they are forbidden from touching those because they might strip out the oil pan when being tightened. I tell him that the reason why the car has had the oversized drain plug is because some mook who provided service to the previous owner twenty or more years ago stripped the factory plug and it wouldn't tighten and would constantly drip. When I bought the car nineteen years ago the first thing I did was an oil change and found that the pan was stripped. The simple solution is to install a self threading oversized drain plug which will "install" the proper thread size in the oil pan on the way in. It's been that way for a successful nineteen years. He says firm no and I buy the FL1A and take the car home where, with a lot of pain, I roll around on the driveway and do my own stinking oil change. At least they didn't use the United Airlines policy excuse and drag me out of the waiting room by the ankles.
    Mach1 Driver and Grabber70Mach like this.
  8. RagTop

    RagTop Old Grumpy

    At least my no A/C car has a drop top. I can't imagine operating a coupe or sedan up here without A/C. Especially a dark colored exterior and interior. I'll bet you could have baked bread in that car in the summer in Placerville. I used to park my 2000 Z28 with a black interior in my driveway and, on a normal summer afternoon, you'd have to wear oven mitts to deal with the black leather covered steering wheel.
    Last edited: Apr 11, 2017

    KBMWRS What did the moron say today?

    Ken let me know next time and I'll drop by and do it for you. No problem. Or you can drive down here. Doesn't matter to me. Just ask...I'll be there.
  10. c6fastback

    c6fastback Member

    Towel heat on steering wheel or sun reflector in windshield was mandatory along with sheepskin seat covers or a towel to sit on . Wearing shorts and sitting on hot black seats was brutal
  11. RagTop

    RagTop Old Grumpy

    Mike, pretty long run from Morgan Hill to Lincoln just to change my oil.:) Thanks for the offer though.
  12. KBMWRS

    KBMWRS What did the moron say today?

    Hey that's why i have a motorcycle or vette....I love to ride/drive. You just let me know I'll be there.
  13. Patrick Stapler

    Patrick Stapler Active Member

    I agree with Z. He turned me onto Mobil 15W-50. I ran it all this past Summer/Fall/Winter. I only have a stock gauge, but could tell no difference in readings regardless of outside temperature. $25/5quarts at Wolly-World.
  14. David67

    David67 Active Member

    Hey I'm only 25 miles from you in Sacramento (Arden Arcade area). If you need a hand let me know. Also it'll give me a reason to drive the mustang since I have a daily driver now.

    Sent from my Pixel XL using Tapatalk
  15. Starfury

    Starfury Active Member

    Hey, that's three of us up here. I'm in Elk Grove :D
  16. David67

    David67 Active Member

    SacBill lives 3 blocks from me so that's four.

    Sent from my Pixel XL using Tapatalk
  17. bartl

    bartl Old Fart

    Okay...... I'll add my $0.02 on this...

    A. Common Misconceptions.
    1. Oil gets "thinner" with heat. Yes & no. Heat does have an effect on the flowability of oil but viscosity improvers in the oil's "package" make the oil MORE viscous as the oil temperature increases and LESS viscous at lower temperatures.
    2. "Thicker" oil is better than "thinner" oil. Again, yes and no. What determines the proper viscosity that should be used in any particular engine are a) operating temperature of the oil and b) bearing clearances. If the factory specified 10W30 for your engine, and the engine has stock bearing clearances and is operated in the normal temperature range then 10W30 is what you should use. If higher than average oil temperatures are expected then the manufacturer may have recommended a 10W40 over a 10W30.
    3. High pressure or high volume oil pumps are better than standard volume pumps. Again, it depends. If there is a NEED to supply more oil to the bearings that's one thing, but if there ISN'T a need then energy is being wasted, at the cost of horsepower and wear and tear on the engine. Yes, the oil pump consumes horsepower to turn it, just like the hydrostatic pump on your lawn tractor.

    B. In My Opinion...
    1. If you have an issue with oil temperature, then you don't need a "thicker" oil, you need to address your oil temperature "problem". If it's due to higher than normal engine COOLANT temperatures then you need to address THAT issue, first. If oil temperature is an issue aside from coolant temperature then an OIL cooler should be considered. Remember that like any other hydraulic pump, the oil pump will generate heat on a scale that is proportional to the work it is being asked to perform so if you're running at higher rpm, with a more viscous oil (especially a more viscous than needed to lubricate the bearings) then that excess heat is being transferred to the oil, which is the secondary method of engine cooling.
    2. The change in oil pressure as heat increases is as much a function of expansion of the bearing clearances as it is oil viscosity and isn't, necessarily, a bad thing as long as there is a satisfactory "cushion" kept between the bearing and the journal. In fact, extra flow through the bearing REMOVES more excess heat helping to maintain the bearing temperature. So, not only can an increase in viscosity reduce the amount of excess heat carried away from the bearing it can cause the oil pump to work harder and add more heat to the oil. So, while moving to a 15W or 20W50 may make you FEEL better because your oil pressure gauge shows a higher level it may be counter-productive to engine power, heat and wear.

    It's like adjusting Mustang doors.... you adjust the door to the quarter panel and rocker panel, then adjust the front fender to the door. With oil, you "adjust" your oil to the engine bearing clearances at your normal operating temperature, then adjust your cooling system to maintain proper engine coolant and oil temperatures.

    Calculate how much of an oil cooler you need to reduce the oil temperature from its current level to the desired level and add an oil temperature thermostat to maintain an oil temperature of at least 185*F to avoid over-cooling the oil.
  18. zray

    zray who said Beer ?

    An oil temperature gauge is pretty useful in determining if there actually is any MEASURABLE heat being added to the oil due to running a higher viscosity oil. I don't know about 20w-50 oils, but the Mobil 1 15w-50 oil I've been using added 0 degrees to my oil temperature vs. a 0w-40 or a 10w-30 also tried. In fact the oil pressure, as well as oil temperature, with the 0w-40 was identical to the 15w-50. I didn't expect that in 30 degree weather.

    I'll always use the 15w-50 Mobil 1 because it's worked so well under extreme conditions, and has phenomenal wear protection, but I realize that Oil type and brand are much less important than having clean oil, and a clean oil filter.

  19. zray

    zray who said Beer ?

    IMG_1952.JPG I'd like to just throw this red meat out there for all the beasties to maul.

    The only way to get extra oil flow to the bearings is to install a high volume oil pump with bigger than stock gears (or rotors). The viscosity or temperature of the oil will usually affect the oil pressure, but has no impact on the volume that's flowing at any given time.

    Oil flow VOLUME is determined ONLY by the size of the oil pumps gears and the rpm. You may have low oil pressure or high oil pressure depending on the thickness of the oil, but mainly depending on the bearing clearances. But the actual amount of oil moving thru the system depends solely on how much oil the oump can move with each stroke. Since liquid is not compressible, then the oil pump doesn't care if it's pumping oil or water or molasses. The same amount of liquid will leave the pump with each revolution. Thick oil will get to the bearings as quickly as thin oil, because the oil pump is moving the exact same amount of regardless of viscosity, it's just under higher pressure.


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