Mobile 1 rocks. Used it in my last 3 (and current) cars and never had an internal motor issue. A difference of 5W or 10W in winter is small and should really make no difference in it's cold viscosity to prevent a car from starting. If your really concerned get a large battery (say 835 cca) then you know it won't be an issue of your cars motor turning over when its cold.

The latest recommendation from Ford and others is 5W20. That's thinner at both ends! I'd like to hear any comments from mechanics on any detrimental effects they've seen, if any.

NK -

As others have indicated, you'll have no problems running 5w-30 year round. 5w is a bit more expensive than 10w, but only by pennies. Multi-vis protection levels (by today's standards) are the same between 5w and 10w.

There is a significant difference in viscosity in cold temps between 5w and 10w however, and I'd be sure to use the 5w during the winter.

Used to be (20 years ago...) that the multi-vis oils broke down sooner than the straight weight oils, but no longer the case with modern oils.

Use ONLY major oils - NOT the unknown or local stuff. We regularly tested oil for use in our equipment (in fact the military spec was/is based off our old testing program), and found the "minor" brands rarely met their own published specs.

On a vehicle like yours, there's no advantage to using synthetics (like Mobil-1), unless you want to throw money away. Ultra high operating temps (above 260F) are where the synthetics are good...

Assuming you change your oil regularly to keep the contaminants out, most engine wear comes during initial start-up, so the 5w really helps here in colder climates.

Al

i dont know why anybody would EVER use 10W30

5W30 is by far superior, REGARDLESS of outside temps

Because my manual specifically calls for 10W-30, and says to ONLY use 5W-30 if the temperatures are routinely below 5F? (which it never is) and to NOT use 5W-30 if it's above 90F (which it often is.)

What you're saying conflicts directly with my manual.

if it was my car i would use 5W30

5W30 and 10W30 are the exact same oil when up to operating temps, they are both 30W.

5W30 is just thinner when the oil is cool, there is no harm with having thinner oil at startup. it circulates through the engine faster.

trust me, ive been to a few 8 hour "oil conferences", it was part of my paid training at jiffy lube. you learn alot listening to somebody talk about oil for 8 hours, lol

Davids:

I've also been doing a bit of investigating to learn a bit more about engine oils.

This web site talks a lot about it:

http://en.wikipedia.org/wiki/Engine_oil

This one suggests that it's not a good idea to use a multigrade oil with a wide operating range, like 0W50, for example.

www.uponone.com/howtos/18.pdf

The reason why is that the way they make an oil into a multigrade oil is by adding polymers called "viscosity index improvers". Basically, these are really long molecules, which coil up when they're cold, and unravel when they're warm.
When they coil up, they have less effect on the oil they're dissolved in, so the oil behaves much as it would if they weren't dissolved in it. However, when the oil warms up, these polymer molecules unravel and effectively act much like a hair clog in a drain. They impart drag on the oil molecules so that they can't move as easily, and the result is that the oil doesn't loose it's viscosity nearly as much as it otherwise would. That is, the long chain spagetti in the oil makes it artifically "thicker" at warm temperatures. But, that spaghetti coils up when cold, so as not to increase the viscosity at low temperatures.

Apparantly, the problem is that these polymers can precipitate out and cake up on the metal parts of the engine, causing things like sticking rings and valves.

The wider the temperature range you want the oil to work well over, the more polymer you have to add to suppress the natural thinning of the oil with heat, and the greater the POTENTIAL for problems.

Another great site is this one:

http://minimopar.knizefamily.net/oilfilterstudy.html

The guy simply bought oil filters and cut them open to find out how well they were made. Basically, the prime selection criteria he looked at were as follows:

1. Filter element size - basically the larger the surface area of the filter, the more dirt it will catch before becoming clogged. When a filter becomes clogged, then there's a bypass valve that allows oil to flow through it unfiltered to ensure the engine at least gets some oil (albeit potentially dirty oil).

2. The kind of filter element - paper filters have larger holes than synthetic media, so they don't filter the oil as clean as synthetic media. Synthetic media also has MORE holes than paper, so even though the holes are smaller, they don't present a flow restriction. Some high performace filters have a hole size gradient in the filtration media so that the largest holes are closest to the upstream face of the filtration media and the smallest are downstream, thereby being able to catch much MORE dirt before needing replacement.

In general, most good quality oil filters use a paper filtration media between 300 and 350 square inches in size. Some oil filters have filtration elements that are 400 square inches in size.

Surprisingly, the filter company that spends the most on advertising, FRAM, spends the least on making good oil filters. The two FRAM filters tested had a paper filtration media of only 193 and 248 square inches; the lowest of all the filters he tested.

The BEST filter and best value oil filter tested turned out to be the same one; the Purolater Pure One filter with a synthetic filtration media that's a whopping 400 square inches in size for only about $5. (the "Nordic Group" web site referred to later on in this post says that a synthetic filtration media has not been shown to provide any tangible benefit over paper filtration media in oil filters)

The best inexpensive filter was the STP filter (made by Champion) with a paper filtration element that's 360 square inches in size (well above the average for inexpensive oil filters) for about $3 (which is typical for a cheap filter).

I particularily like the guy's approach. He throws away all the racing stripes emblazoned on the packaging, and cuts the filters open to see what's inside. Then, he uses good old fashioned common sense to reason that the larger the area of the filtration element, the more dirt the filter can hole, and so the longer that filter will last. We need more of that kind of horse sense in consumer advocacy, and fewer racing stripes on the manufacturer's packaging.

IN SUMMARY:
I think what I'm going to do is stick with 5W30 for all my oil changes. The amount of extra polymer in the oil needed to make for the wider temperature range isn't much. Also, the reason why newer cars call for thinner oil (5W30 instead of 10W30 is because engine tolerances have gotten smaller, so they need a less viscous oil that can flow through those tighter tolerances during start-up better (http://www.nordicgroup.us/oil.htm) And, I'm simply going to buy whatever motor oil I can find with an API SJ rating or higher (SL) cuz it's the sludge that forms in motor oil that's much more of a concern than metal-to-metal contact in the engine. So, according to this guy (http://www.nordicgroup.us/oil.htm), it makes a lot more sense to buy ordinary oil and change it on a regular basis to eliminate the sludge in suspension than buy premium oil (like synthetic oil) and not change it as often. The synthetic oil doesn't break down at high temperatures and flows better at low temperatures, but sludge accumulates in it just as quickly as a cheap oil. Apparantly, even though synthetic oils are better at holding sludge in suspension, they're not that much better that you can change your synthetic oil every 25,000 miles as some synthetic oil manufacturers were originally suggesting.

And, I'm going to phone around to find out who sells STP oil filters (and maybe Purolator oil filters too). I think Wal-Mart sells STP oil filters if I'm not mistaken.

I thank everyone for their time and input.

Nestor,

As I indicated above, while working for Caterpillar (the manufacturer - not a dealer), I had responsibility for product reliability of all of our small engines - up to about 500 inches. In that job, I regularly cut open supplier's oil filters and managed testing of engine oils used both under the Caterpillar brand, as well as those commonly being used by end users in our equipment. The MIL spec is our doing...

The oil filter link you provided reflects basically sound analysis and conclusions, and the results aren't that much different than my own personal studies. And while some manufacturer's total filtration capabilities may be different than others, I submit to you that unless you're in an extremely dirty environment, and change your oil at least every 5,000 miles, you'll never come close to maxing out the filter's capacity. But DO stick with the major brands here... Bypass design and reliabilty were an issue otherwise.

Again, any of the major brand oils will satisfy your automotive requirements. However just to reinforce my previous input... We often found that some oil manufacturers failed to meet even their own specs, let alone the API specs. This was only the case on the "off brands" or local "house brands". Just because the bottle says "Meets or exceeds API..." doesn't mean it did.

The only time I use a "house brand" is when I need a gallon of bar oil for my saw...

Quote:

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And while some manufacturer's total filtration capabilities may be different than others, I submit to you that unless you're in an extremely dirty environment, and change your oil at least every 5,000 miles, you'll never come close to maxing out the filter's capacity.

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OK, if that's the case, that brings us back to the question of whether or not the filter should be changed with every oil change. If the filter isn't anywhere near loaded to it's capacity, then wouldn't it be sensible to replace the filter on every 2nd or even 3rd oil change instead?

Everyone I know replaces the filter with each oil change, but I'm aware that car manufacturers used to recommend changing the filter every 2nd oil change. I don't know if that's still their recommendation.