Viscosity and Extended Drains

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The comments you have heard seem to be overly general and may not apply to your application. My comments on extended drains are that every car and every driving style are different. What your car likes and how your driving style affects the ability of your oil to withstand extended drains may be very different from a guy next door with the same type of car. Viscosity should not have a major effect on an extended drain test. The difference between a particular 5W30 vs. the same brand 10W30 should be almost negligible imo. My advice is pick an oil you like, run it for 5000 miles, have it tested, and then decide if you can go farther. There are plenty of folks here who will help you interpret your results. Having said that, if your car is under warranty I would not suggest that you exceed your manufacturers drain interval recemmendations. Don
 
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I can only answer relative to Mobil 1. Some cars consume the 5-30 much faster than the 10-30 and some do not. The 10-30 has a much better NOACK volatility, so less makeup should be needed. The 10-30 should be more stable, but it doesn't make a difference in all cars. Given the same amount of makeup oil added, the tbn would be virtually the same at 7.5K Either will have adequate tbn. [Big Grin] You will need a decent filter and keep your engine in shape to keep the insolubles within range.
 
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FWIW, the Mobil1 granted GM's european Long Life spec (running up to 18K miles or 2 years by the oil change light) is their 0W-40. My guess is Viscosity is not the key factor. Edit: One more thing...Mobil1 says you can go "the maximum mileage or time listed in your owner's manual" on any of their viscosities. I'm using 5W-30 in one car and 0W-20 in another, and plan on 7500 miles/1 year (ie the max mileage or time listed in my manuals)...
 
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I disagree that viscosity doesn't matter. Although there are "newer" oils that claim long-drain OCI's (eg. Castrol SLXII), I have found that as a general rule of thumb, an oil needs to be A3 rated in order to do well on extended drains. OR you need to have a higher cojone viscosity base oil when it comes to dino oils. That is, A3 rated synth. oils will: 1. Stay cleaner longer 2. Be consumed less 3. More oxidatively stable. That is why Europe and Euro engines have had a fit with non-A3 synth. oils that are really unfit to go 10k mi. OCI's. eg. M-1 5-30. That said, a 5-40 or 5-50 is better for extended OCI's than a 5-30 (assuming outside temps >50F). Likewise, in order to safely do extended-OCI's with dino oil (eg. 10k mi.) you better have a 15-40 or 20-50 because a dino 5-30/10-30 ain't gonna cut such an interval. That is why we do 3k OCI's with 99 cent dino in N.A. and call it a day...
 
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I agree 100% with Dr. T [HAIL 2 U!] The BMW oil is a thick 30 weight oil,just like GC and Amsoil. They are almost a 40 weight. Look at the heavy duty oils for the big rigs and compare them to Mobil 15w50 or any 50 weight synthetic and you will find almost the same amount of phosphorus,calcium and zinc. [Big Grin]
 

Don Stevens

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I need some help with the A3 rating as I do not know what this means. I think I saw a post about "What does A5 mean?" Can someone enlighten me or send me to a thread that has definitions of the "A" ratings? Don
 

Al

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quote:
Originally posted by RedWolf4000: Does anyone know the effects that viscosity changers have on the extended drain of Mobil 1, or any other synthetic oil? Some oils like Mobil 1 0W-40 will initially thin out and then thicken as life increases. I would say though in general we see oils that will shear down over time. Has anyone run any tests or have any insight on what oil would do the best in extended drain? Mobil1/Amsoil/Delvac have shown time and again that they are good for the longer haul Example, would a 5w-50 have a shorter life period then somthing less stretched like a 10w-30? in theory the closer the numbers the the better the oil will hold up-but the Mobil 1 5W-30 and 10W-30 both hold up about the same i used a 5w-30 oil and most people i talk to are telling me to use a 10w-30 because it will serve better in my 7500 mile OCI. Is this true? In general yes but in N.Y. you are better off with a 5W and as mentioned Mobil 1 5W does well
 
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Don Stevens. The A1,A3 and A5 ratings are European specs for synthetic oils. A3 and A5 rated oil is for long drain. The A1 and A5 oils are low viscosity with the HT/HS vis. less than 3.5 cSt at 150 deg.C. A3 rated oils are higher viscosity oils (ie. 40 & 50 weight) that has a HT/HS vis. of 3.5 or greater at 150 deg. C. Some 30 weight oils meet the A3 rating like BMW 5w30, German Castrol 0w30 and Amsoil 5/10w30. This is as simple as I can explain it. I hope this helps.
 
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Does anyone know the effects that viscosity changers have on the extended drain of Mobil 1, or any other synthetic oil? Has anyone run any tests or have any insight on what oil would do the best in extended drain? Example, would a 5w-50 have a shorter life period then somthing less stretched like a 10w-30? i used a 5w-30 oil and most people i talk to are telling me to use a 10w-30 because it will serve better in my 7500 mile OCI. Is this true?
 

Don Stevens

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Thanks 2K and Jason. I'll check it out. Jason, Aren't you the guy I had a few discussions/debates with on Bimmerforums a few years ago? Roadfly maybe? Don
 
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