I have a 1994 Mercedes C-280; according to a link from ask.com the motor oil grade recommended is 5W30. I’ve used some of that. Is there any advantage to that over 10W40?
Engines are designed for oils of a specific viscosity. If you use too heavy of an oil then the engine has to work harder to slosh all that heavier oil around, which reduces your fuel economy and wears your engine out faster. If you use a lighter oil than recommended, then the parts won’t be properly lubricated and your engine will wear out quickly from the resulting friction.
Most engines have a range of oils that vary according to the outside temperature. If you look in your owner’s manual there’ll be a chart that show what oils you can use over what temperature ranges. 5W30 probably covers most temperature ranges. If you are in an area that has very cold winters, you may want to go with 5W30 in the winter. Conversely, if you are in an area with very hot summers, you may want to use 10W40 in the summer. For most regions in the US, one oil type will typically be ok all year long.
One advantage of heavier oils is that they help when you have older engines that are pretty well worn, and you have greater gaps in things like the bearings and piston rings. A twenty-something year old engine may burn or lose more oil using the lighter 5W30 vs 10W40.
Just make sure that whatever oil viscosity you use is within the ranges given in your vehicle’s owner’s manual.
It flows more readily. This is particularly helpful during a cold start (e.g. when the engine has sat overnight), which is when most wear occurs.
Ford issued a technical service bulletin in 1999 that called for using 5W30 for any gasoline engine regardless of model year. Thus all previous recommendations for 10W30 etc. were superseded. The bulletin said in part "Tests have proven SAE 5W-30 viscosity grade motor oil provides the optimum protection and benefits for Ford gasoline engines. At both high and low ambient temperature conditions, SAE 5W-30 provides the best overall protection."
Some old gearheads were aghast because they had the notion that higher viscosity numbers meant better protection. They weren’t considering that it doesn’t matter how wonderful the oil is if it can’t get to where it’s needed in time. Heck, some late model engines call for 0Wxx oil.
All that said, if you aren’t an automotive engineer or tribologist (lubrication expert), then you deviate from the manufacturer’s specifications at your own risk.
I got a little curious about the question because I had absolutely no idea what 10W-40 even meant and found this page, which as a complete layman I think breaks the whole thing down quite nicely. I do, however, yield to tribologists with more experience.
Well, I live in Los Angeles County in California, where the temperature never reaches freezing levels in winter–not in the last 60 years or so. I needed to get oil for the car and I didn’t have the manual handy to get the right information.
I talked to a guy once who worked in an open pit mine in northern Canada, and he remembered that someone destroyed two giant diesel engines by not letting the oil warm up before starting them after the trucks had sat outside all weekend in the winter. I seem to recall some older cars in Canada recommended 5W30 for winter oil, 10W40 for summer - because in the winter the oil needed to flow better when cold, in summer you wanted the oil to flow thicker.
There’s also the story I heard from an interview with an old-time bush pilot about flying northern Canada in the winter in the 1930’s, 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. When it was time to take off the next morning, they’d dig around in the snow, pick up the oil puddle, roll it up (!) and bring it indoors and get it boiling in a pot. then they’ pour it into the cold engine, and they had about 5 minutes to get the engine started. The days before 5W30…
I guess that works fine if you live where it snows in winter.
This is the first time I’ve heard that one.
It was definitely standard practice to drain the warm oil into a bucket and take this indoors to keep it warm. The “roll it up, then warm it up” scheme sounds remotely possible, but not like something you’d want to do routinely (among other problems, too easy to get the oil contaminated with dirt).
It’s definitely true that if you left oil in the engine as it cooled to, say, -20 F you had a major struggle on your hands to get the engine started again.
Yeah. I was wondering why drain it onto the snow and go through all that mouse motion instead of just draining it straight into the pot.
Gary
I hadn’t heard about that. I get how viscosities work, and why a thicker/thinner would be better for different engine considerations. But would you take that 5W30 for all engines literally? I ask because I have a 67 Olds, and find oil consumption is much higher with lower viscosities. Now, what of that is due to age, and what is due to 1967 tolerances I don’t know, but I would assume that even a brand new 1967 car would eat a lot of 5W30- no?
How about a 1994 Mercedes as opposed to a 2017 model?
Well, that’s for all Ford gasoline engines – Ford doesn’t get to issue instructions to other manufacturers – up to that year, and yes I would take it literally. There’s a lot more to motor oil than just the viscosity numbers, and it’s certainly plausible that a 5W30 with the right additive package (friction modifiers, film strength enhancers, etc.) is more than adequate for all the engines covered by the bulletin.
Oil consumption is a different issue.
Of course Ford’s recommendation is for their own vehicles, but presumably the logic would apply to others as well- that being that the modern 5W30 is better than the straight-30 originally specified for a 67, or the whale semen used in a Model T (OK, I have no idea what a model T used)
But I think what you’re saying is that the 5W30 would be preferred *irrespective *of its impact on consumption- ?
I *think *what he meant was that Ford’s bulletin was considering lubrication and lubrication alone. With no regard to any impact plus or minus on consumption.
A properly maintained engine doesn’t consume any meaningful amount of oil. If it is consuming oil, it isn’t “properly” maintained. Yes, as a practical matter you *can *run it another 100K miles while it’s burning oil. But that’s not what the factory engineers would prefer that you to do.
If you want to choose an oil for your vehicle with an eye to minimizing consumption, go right ahead. But understand you’re now compromising on (at least some aspects of) lubrication to do so.
I’ll take a little issue with that. Most modern engines consume little to no oil until and unless something is wrong. But my experience is that in the good old days (probably pre-1990, but maybe before that) cars often consumed a noticeable amount of oil right from the factory. Try going to a Buick dealership in 1972 and complaining that you’re consuming a quart every 1500 miles.
I understand what you’re saying- but my original question came about because I was surprised to hear Ford would recommend the 5W30 for cars built in an era of much lower tolerances. I do understand that a 5W30 will behave like a 30W at operating temperature, and so maybe the short periods where it flows like a 5W are not significant.
Gary T was referring to a Ford Technician Service Bulletin (TSB.) TSBs are sent to dealer service departments and usually only apply to vehicles recently produced at the time the TSB was issued. i.e. cars/trucks the owner is likely to take to the dealer for service.
I highly doubt a TSB released in 1999 was intended to say you can go ahead and use 5W-30 in your 1958 Edsel Pacer.
Well, this is fine for Ford, especially, and Buick. But I was asking about my make of car…
you answered your question in your OP. you found the recommended grade is 5W-30. No, there is no advantage to using anything different.
One of my cars, a KIA, recommends 0W-20 year round.
Something else to remember about motor oils besides the viscosity is the API grade. The owner’s manual should specify both.
Yeah, not sure what you are asking. Use what your car’s manual calls for. 5W-30. So, just use that. Why do you want to use something else?