# Motor oil grades: 5W30, 10W40; what's the difference? for particular makes **URL:** \ **Category:** Factual Questions\ **Created:** [October 27, 2017, 5:00am UTC](https://boards.straightdope.com/t/motor-oil-grades-5w30-10w40-whats-the-difference-for-particular-makes/799952 "2017-10-27T05:00:54Z")\ **Posts on this page:** 19\ **Page:** 3
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [October 30, 2017, 5:44pm UTC](https://boards.straightdope.com/t/motor-oil-grades-5w30-10w40-whats-the-difference-for-particular-makes/799952/41 "2017-10-30T17:44:38Z")
They totally do. BMW has their own standards that don’t exactly gibe with MB’s which don’t exactly align with the EU’s. And certainly not with SAE’s. The one and only oil sold in the USA which meets BMW’s standards is theirs. ---
**Author:** ![SigMan](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@SigMan](https://boards.straightdope.com/u/SigMan)\ **Post date:** [October 30, 2017, 5:47pm UTC](https://boards.straightdope.com/t/motor-oil-grades-5w30-10w40-whats-the-difference-for-particular-makes/799952/42 "2017-10-30T17:47:32Z")
> [@Kimballkid](#): > > Just as a data point, my 2004 Ford Fi50 with the Triton 5.4 liter V8 calls for 5W-20 oil designed for gasoline engines. It does not specify synthetic but the Ford part number is for synthetic blend. My Taurus calls for 5W20 and I put in synthetic oil this time. It’s a 2003 but still hasn’t seen 100K on the clock yet but very close, it’s 96+K. I can say that this oil made my engine run so smooth and more power but the MPG is pretty much the same. Also this oil and the 93 octave gas (I have a flex fuel engine) had made my car more horsepower and response. It’s my sweet chariot. 🆒 ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [October 30, 2017, 6:04pm UTC](https://boards.straightdope.com/t/motor-oil-grades-5w30-10w40-whats-the-difference-for-particular-makes/799952/43 "2017-10-30T18:04:37Z")
> [@SigMan](#): > > … > Also this oil and the 93 \*\*octave \*\*gas (I have a flex fuel engine) had made my car more horsepower and response. > … Bolding mine. A car with such dynamic range and tonal clarity that even hard core audiophiles are impressed. 😃 93 octaves is like DC to well past gamma rays. ---
**Author:** ![Pork\_Rind](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pork_rind/32/111_2.png) [@Pork\_Rind](https://boards.straightdope.com/u/Pork_Rind)\ **Post date:** [October 30, 2017, 6:27pm UTC](https://boards.straightdope.com/t/motor-oil-grades-5w30-10w40-whats-the-difference-for-particular-makes/799952/44 "2017-10-30T18:27:34Z")
> [@LSLGuy](#): > > The one and only oil sold in the USA which meets BMW’s standards is theirs. That’s not correct. BMW’s current spec is LL-04, of which there are oils from Castrol, Mobil and Pennzoil available (there are more, but that’s as far down the list as I cared to go). [LL-04 oil list](https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&ved=0ahUKEwirqbvx-5jXAhVRzGMKHV13DI8QFghCMAI&url=https%3A%2F%2F5series.net%2Fforums%2Fattachments%2Fe60-discussion-2%2F139910d1359582692-mobil-1-0w-40-ll01-vs-ll04-bmw-ll-04-approved-oils.pdf&usg=AOvVaw1eIQiBUhPiGw1BrgV4zGCG)(warning, PDF) ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [October 30, 2017, 6:56pm UTC](https://boards.straightdope.com/t/motor-oil-grades-5w30-10w40-whats-the-difference-for-particular-makes/799952/45 "2017-10-30T18:56:43Z")
> [@LSLGuy](#): > > They totally do. BMW has their own standards that don’t exactly gibe with MB’s which don’t exactly align with the EU’s. And certainly not with SAE’s. > > The one and only oil sold in the USA which meets BMW’s standards is theirs. it’s spreading. GM specifies the viscosity index but then _adds_ their own additive package requirements. Try to find oil meeting “dexos 2” on the shelf. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [October 30, 2017, 6:58pm UTC](https://boards.straightdope.com/t/motor-oil-grades-5w30-10w40-whats-the-difference-for-particular-makes/799952/46 "2017-10-30T18:58:35Z")
ETA: @ **Pork Rind** just above. I don’t know where that document comes from, but I do note that up top in paragraph 4.0 it says that LL-04 oils are not to be used outside Europe. AFAIK the BMW standard for US is something other than LL-04. As well, the majority of oils listed are of European manufacture. While some US companies are represented in the list, a careful look at many (though perhaps not all) of the specific flavors show they are not sold in the US. e.g. you can certainly buy various types of “Mobil 1” in the US. But their own website says you can’t buy “Mobil 1 ESP” As an experiment I went here: [What type of oil and oil filter for my car? Car oil recommendation | Mobil™ Motor Oils](https://mobiloil.com/en/product-selector) and tried entering various years and models of US-version BMWs. The older model years came back as “BMW recommends an oil meeting their LL-01 standard. Mobil 1 has no such oil.” The 2017 model year came back as “BMW recommends an oil meeting their LL-14FE standard. Mobil 1 has no such oil.” I’ve had similar experiences from Castrol’s website. I have no doubt I could buy a non-BMW branded euro-spec oil over the internet and have it shipped to me. But if I want to buy some down at the local car parts joint I’m (BMW officially) screwed. And even then I’d not be following the BMW spec since LL-04 oils are not approved for use with non-EU fuels. Bottom line: I might be wrong in my earlier assertion, but this doc doesn’t seem quite as definitive as it might at first appear. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [October 30, 2017, 7:01pm UTC](https://boards.straightdope.com/t/motor-oil-grades-5w30-10w40-whats-the-difference-for-particular-makes/799952/47 "2017-10-30T19:01:20Z")
> [@SigMan](#): > > My Taurus calls for 5W20 and I put in synthetic oil this time. It’s a 2003 but still hasn’t seen 100K on the clock yet but very close, it’s 96+K. > > I can say that this oil made my engine run so smooth and more power but the MPG is pretty much the same. Also this oil and the 93 octave gas (I have a flex fuel engine) had made my car more horsepower and response. > > It’s my sweet chariot. 🆒 I highly doubt this is anything other than confirmation bias. the wheezy pushrod Vulcan V6 isn’t going to get more horsepower out of an oil change and running premium. your engine is set up to be able to burn any blend of gas and ethanol up to 85% eth. It just has the _ability_ to do so, it will not make any more power with high octane blends. it’s a wheezy, pushrod, cast iron lump. ---
**Author:** ![Lightray](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lightray/32/391_2.png) [@Lightray](https://boards.straightdope.com/u/Lightray)\ **Post date:** [October 30, 2017, 8:41pm UTC](https://boards.straightdope.com/t/motor-oil-grades-5w30-10w40-whats-the-difference-for-particular-makes/799952/48 "2017-10-30T20:41:18Z")
> [@LSLGuy](#): > > IANA lube engineer. Far from it. But as a long-ago motorhead who still drives performance cars and reads heavily but doesn’t wrench much any more my personal POV is:A) The only GQ answer is “whatever the engine manufacturer says.” > B) Any other supposedly factual info is so tainted by marketing hype and Old Wive’s Tales as to be no better than rolling dice. > C) Excluding Artic or Middle Eastern extremes of temperature, any difference in oil performance in any given vehicle will be indistinguishable. The engine either keeps running or fails. You’ll never have a control for your experiment so you’ll never know whether your choice of oil helped, hurt, or had no effect. > D) It’s far more likely that oil and especially filter changes at the correct interval\* are more beneficial to old engines than are any particular viscosity. I _do_ make motor oils, and that’s basically what I’d recommend, too. If you don’t have your user manual or it’s an older model, call the dealer or manufacturer customer service and ask for an oil grade recommendation. For older cars, changing the viscosity grade may help reduce oil loss, but probably will also mess up your engine efficiency. What you want is an oil with a higher treat rate of seal-swell agents. Brands that market a “Max Life” oil are formulated for older cars to have better seal performance. ---
**Author:** ![SigMan](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@SigMan](https://boards.straightdope.com/u/SigMan)\ **Post date:** [October 30, 2017, 10:17pm UTC](https://boards.straightdope.com/t/motor-oil-grades-5w30-10w40-whats-the-difference-for-particular-makes/799952/49 "2017-10-30T22:17:42Z")
> [@LSLGuy](#): > > Bolding mine. > > A car with such dynamic range and tonal clarity that even hard core audiophiles are impressed. 😃 > > 93 octaves is like DC to well past gamma rays. WTH? LOL! I meant octane but I’m a musician so I still think like a musician. 😃 ---
**Author:** ![dougie\_monty](https://avatars.discourse-cdn.com/v4/letter/d/439d5e/32.png) [@dougie\_monty](https://boards.straightdope.com/u/dougie_monty)\ **Post date:** [October 30, 2017, 10:39pm UTC](https://boards.straightdope.com/t/motor-oil-grades-5w30-10w40-whats-the-difference-for-particular-makes/799952/50 "2017-10-30T22:39:24Z")
> [@SigMan](#): > > My Taurus calls for 5W20 and I put in synthetic oil this time. It’s a 2003 but still hasn’t seen 100K on the clock yet but very close, it’s 96+K. > > I can say that this oil made my engine run so smooth and more power but the MPG is pretty much the same. Also this oil and the 93 octave gas (I have a flex fuel engine) had made my car more horsepower and response. > > It’s my sweet chariot. 🆒 Coming for to carry me home… 😃 ---
**Author:** ![SigMan](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@SigMan](https://boards.straightdope.com/u/SigMan)\ **Post date:** [October 31, 2017, 12:21am UTC](https://boards.straightdope.com/t/motor-oil-grades-5w30-10w40-whats-the-difference-for-particular-makes/799952/51 "2017-10-31T00:21:38Z")
That’s right mate. It brings me home every time. 🆒 ---
**Author:** ![excavating\_for\_a\_mind](https://avatars.discourse-cdn.com/v4/letter/e/e8c25b/32.png) [@excavating\_for\_a\_mind](https://boards.straightdope.com/u/excavating_for_a_mind)\ **Post date:** [October 31, 2017, 12:54am UTC](https://boards.straightdope.com/t/motor-oil-grades-5w30-10w40-whats-the-difference-for-particular-makes/799952/52 "2017-10-31T00:54:48Z")
Most every older Mercedes mechanic shops I’ve been to seem to always use Castrol Edge Fully Synthetic 0W40 (Euro Blend) for Benz’s of this vintage. Whether or not you need a fully synthetic oil is debatable, but they do have the benefit of only needing changing once a year (under normal driving conditions). If it was my car, I think that is what I would use. The higher cost, over a year, is negligible and the worst thing that is going to happen is someone may tell you that you are paying too much for motor oil. You certainly are not going to do any damage to the engine by using it. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [October 31, 2017, 2:02am UTC](https://boards.straightdope.com/t/motor-oil-grades-5w30-10w40-whats-the-difference-for-particular-makes/799952/53 "2017-10-31T02:02:37Z")
> [@SigMan](#): > > WTH? LOL! > > I meant octane but I’m a musician so I still think like a musician. 😃 Spellcheck strikes again. Making Dopers it’s bitch since 2010\*. 😃 ========= - The SDMB dates from even earlier but those early browsers didn’t have spell check. 🙂 ---
**Author:** ![SigMan](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@SigMan](https://boards.straightdope.com/u/SigMan)\ **Post date:** [October 31, 2017, 2:53am UTC](https://boards.straightdope.com/t/motor-oil-grades-5w30-10w40-whats-the-difference-for-particular-makes/799952/54 "2017-10-31T02:53:35Z")
Well, spellcheck won’t see anything wrong because it’s not misspelled, just a wrong word. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [November 1, 2017, 3:18am UTC](https://boards.straightdope.com/t/motor-oil-grades-5w30-10w40-whats-the-difference-for-particular-makes/799952/55 "2017-11-01T03:18:49Z")
I was assuming you typed a misspelling somewhere near octave & octane. Maybe like “octar”. Then it silently chose “octave” as its choice and you never noticed what it did. You intended “octane” and saw “octane” despite the word it picked having actually been “octave.” That’s the usual way an almost-right-but-inappropriate word get inserted into many people’s typing. Happens to me regularly. If you double-clutched it yourself without help then that’s different story. ---
**Author:** ![dougie\_monty](https://avatars.discourse-cdn.com/v4/letter/d/439d5e/32.png) [@dougie\_monty](https://boards.straightdope.com/u/dougie_monty)\ **Post date:** [November 1, 2017, 3:59am UTC](https://boards.straightdope.com/t/motor-oil-grades-5w30-10w40-whats-the-difference-for-particular-makes/799952/56 "2017-11-01T03:59:45Z")
Look in Ambrose Bierce’s “The Devil’s Dictionary” under the entry “Editor.” I agree with Bierce, at least when it comes to the way the so-called, “Smartphone” does its gratuitous editing. ---
**Author:** ![md2000](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@md2000](https://boards.straightdope.com/u/md2000)\ **Post date:** [November 2, 2017, 5:06pm UTC](https://boards.straightdope.com/t/motor-oil-grades-5w30-10w40-whats-the-difference-for-particular-makes/799952/57 "2017-11-02T17:06:03Z")
> [@LSLGuy](#): > > I was assuming you typed a misspelling somewhere near octave & octane. Maybe like “octar”. Then it silently chose “octave” as its choice and you never noticed what it did. You intended “octane” and saw “octane” despite the word it picked having actually been “octave.” > > That’s the usual way an almost-right-but-inappropriate word get inserted into many people’s typing. Happens to me regularly. If you double-clutched it yourself without help then that’s different story. Annoyed Employee waving a memo: “My name is _Myron_, not moron! next time don’t just take the first word spell-checker suggests!” Pointy-Haired Boss: “What’s spell-checker?” ---
**Author:** ![SigMan](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@SigMan](https://boards.straightdope.com/u/SigMan)\ **Post date:** [November 2, 2017, 5:39pm UTC](https://boards.straightdope.com/t/motor-oil-grades-5w30-10w40-whats-the-difference-for-particular-makes/799952/58 "2017-11-02T17:39:10Z")
^^^:p:D^^^ ---
**Author:** ![mixdenny](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mixdenny/32/2962_2.png) [@mixdenny](https://boards.straightdope.com/u/mixdenny)\ **Post date:** [August 15, 2020, 5:21am UTC](https://boards.straightdope.com/t/motor-oil-grades-5w30-10w40-whats-the-difference-for-particular-makes/799952/60 "2020-08-15T05:21:14Z")
> [@md2000](#): > > in weather close to -20 or -30 (or worse). He said they’d land in a remote community, and quickly run around to the front of the airplane and take out the oil plug and let the engine oil pour into the snow Somewhat related is the use of Castrol oil in racing cars in the 1950s and 60s. The vegetable based oil had a large following but it could congeal after being subjected to the high temperatures of the hot racing engine. The mechanics would drain the oil and heat it up before pouring it back in the engines the next day. Could be an old racing wive’s tale, I guess. [Previous page](https://boards.straightdope.com/t/motor-oil-grades-5w30-10w40-whats-the-difference-for-particular-makes/799952.md?page=2)