Oil Question - The difference between 10w40 and 5w30?

Hi,

I have recently put 10w40 into my 1.25 1997 Ford Fiesta. Since then i have experienced engine rattling when accelerating in high gears.

Would this be because i have put in 10w40 oil instead of 5w30?

What is the difference? and What is the rattling?

16 Answers

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  • 1 decade ago
    Favorite Answer

    The base viscosity of 10W-40 oil is indicated by the 10, so it is a thicker oil than the 5W-30. Both oils are rated for use in winter (the W), and the last number is their maximum cold-weather viscosity - again the 10W-40 is thicker, with a viscosity of 40 versus 30.

    Always run the manufacturer's recommended weight oil in your vehicle, regardless of how many miles is on the odometer. Your Fiesta's 1.25 liter engine was designed to run with a specific oil, and moving up to a thicker oil like 10W-40 is only making the engine work harder and costing you gas mileage. If you are looking to improve your engine's protection, change from a conventional oil to a synthetic blend or a full synthetic oil.

    If the vehicle is high-mileage, and you're wanting some extra protection for that reason, there are a number of oils available specifically formulated for high-mileage vehicles. I have a 1994 Ford F-150 with 281,000 miles on it, and I use Valvoline MaxLife Synthetic Blend oil in it - and I'm still running the 10W-30 weight that Ford recommended for that particular truck.

    Finally, if you're trying to address an issue such as smoking or loss of compression, you can try an engine oil additive (although a trip to your mechanic is recommended instead). If you do use an additive, don't waste your time with a "viscosity enhancer". They just make your oil thicker and make your engine work harder, just like switching to 10W-40. Pick an additive that is designed to fill in scoring marks on the piston walls, such as Restore (silver and black can, comes in 2, 4, and 8 cylinder sizes, you can find it at Wal-Mart, and most auto parts stores).

    As a side note, are you certain this is an engine rattle, and not cylinder "knock", which is caused by pre-ignition of the gas and might be an unrelated problem?

    Source(s): I managed a combination lube shop and auto parts store for over six years, doing an average of nearly 100 oil changes per day, and over a million dollars in sales of oil products per year. HowStuffWorks oil article: http://auto.howstuffworks.com/question164.htm Mobil Oil FAQ page: http://www.mobiloil.com/USA-English/MotorOil/Oils/...
  • Anonymous
    4 years ago

    RE:

    Oil Question - The difference between 10w40 and 5w30?

    Hi,

    I have recently put 10w40 into my 1.25 1997 Ford Fiesta. Since then i have experienced engine rattling when accelerating in high gears.

    Would this be because i have put in 10w40 oil instead of 5w30?

    What is the difference? and What is the rattling?

    Source(s): oil question difference 10w40 5w30: https://trimurl.im/a72/oil-question-the-difference...
  • Anonymous
    1 decade ago

    both are multigrades.numbers indicate ranges covered.5 being thin and easy flowing(for hot running)and 30 being thicker(correctly more viscous)80 or 90 being gear box oil.on a cold day the requirements are different from a hot one.Pre multigrades oil was a straight "weight"and you changed your sae 30 for seasonal requirements.SAE 30 is still in use but for predictable running conditions.ie a lawn mower or cement mixer that dont experience the far more varied running conditions of a car.I make it a rule to observe manufacturers recommendations.change the oil and see if it reverts.oil's cheap,engines are not.

  • rozele
    Lv 4
    3 years ago

    5w30 Vs 10w40

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  • 1 decade ago

    The oil differences have being answered above, the rattling under load in high gears is is 'pinking' caused by low grade fuel, (have you filled up at a different place lately?) or ign. timing (too far advanced) worth a trip to your garage for checking as over being advanced can be harmful to the engine..

  • 1 decade ago

    10w40 is much thicker and is more suited for a warm climate >11 degrees. 5w30 is thinner and should be used for cars in the u.k. a thicker oil shouldn't cause anty rattling as it is thicker. the rattling could be an unrelated fau;t such as alternator etc

  • 1 decade ago

    depends most likely its cheap gas so id first do a tune up replace the fuel filter and add a fuel treatment 10w 40 is thicker and shouldnt casue any knock if anything should have help some with the age of...rattling when accelerating would be either low octane or bad plug

    • Jerry6 years agoReport

      There is no such thing as cheap gas. All gasoline has to meet government specifications.

  • 3 years ago

    Add veggies to baked items. You'll never even taste the particular zucchini in these brownies or maybe the sweet potato in these cookies.

  • 1 decade ago

    numbers show the viscosity of the oil

    ask an auto parts store what is best for your weather and area

    engine pinging - does it disappear when you use a higher grade of gasoline?

    all the best

  • ?
    Lv 7
    1 decade ago

    5w or 10 w both are ok with that engine but if it has been running on a thicker oil the hydraulic presser sensor is most likely shot . its either your hydraulic valve followers that are rattling or you have a big end problem

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