Mobil 1 for my Diamond in the Rough

[Iain]

I purchased an almost pristine 2001 British Racing Green Taurus SES with 3.0L Duratec V-6 last spring. I had been looking for it for several months at the time and now that I have it, I want it to last as long as possible.

I've been lurking here since then, gathering information as to ways to smooth out it's rough edges; I suspect the original owner didn't maintain it properly, so the very first thing I did was get a dino oil change with a new Wix oil filter so as to flush out the old oil. 1500 miles later, I replaced that oil and filter with Mobil 1 5W-30 and a new Wix filter.This engine loves Mobil 1 as that had a significant impact on performance.

The point of this post concerns the 5W-20 v. 5W-30 weights of Mobil 1 oil.

Mobil recommends an initial shortened OCI of 3000 miles which I'm 2000 miles into now. I want to install 5W-20 next but I'm hesitant to install it straightaway, so I'm considering an even mixture of both weights for the upcoming oil change. Can you say 5W-25?

The question then is, since these weights comply to different Ford specifications will they be compatible? I've read some horror stories of "custom" mixtures and their aftermath in this forum and I don't want that to happen to my Taurus.

 

[M3 Mitch]

I think you could use either one. The 5-30 will give you a *bit* more film strength at higher loads and higher temps, the 5-20 *may* give you a bit more MPG.

I would pick one or the other and go with it. If you make more short trips and slower speeds, at colder temps, go 5-20 and in Fairfax county in the winter I would think this is you.

But, maybe not, if you are a bit of a lead foot or spend most of your time on the Interstate, go 5-30.

But you can't go wrong with either.

There is probably nothing wrong with mixing the 2 grades to make a 5W-25, probably this is technically sound, but I don't think it's worth the effort.

Either weight of M-1 will see the engine last way longer than the body there in salt country. IMHO anyway.

If you want to obsess, obsess about the filter - but that's a different part of the forum...

BTW have you changed the trans. oil, brake fluid, PS fluid, etc? I think these would reward your efforts more than splitting hairs on these 2 excellent oils.

 

[vronline]

I run Mobil 0W40 in my Taurus and it's doing great! I would pick one weight and go with it rather than mixing...

 

[Quockieo]

If you do alot of high rpm driving, stop and go, mostly street driving, etc. go with 5W30 if your manual states it. If not go with 5w20 if manual permits it to do so. 5w20=better mpg. I wouldn't ever mix, just stick to one for what it's worth.

 

[J Dub]

the 3.0 Duratec in my Mazda calls for 5W-20. That's what it gets. No complaints here.

 

[vronline]

I'm curious how much of a difference in gas mileage one could expect from using the thinner weight oils? I just switched from 5w30 Castrol Syntec to 0w40 Mobil 1 and haven't noticed any real difference at this point. I haven't put on enough miles yet to get a valid comparison at this point however...

 

[Curious Kid]

As far as the MPG difference between +/- 1 weight is apt to be lost in the variables of operating conditions (traffic jams, hitting every red light, quality of gas, etc.). When things are smooth going for some time though it migh present itself on the order of .5% if I recall correctly. I remember in school how human error could be factored in as 5%, so add for instrument error, and so forth...well you get the picture.

Tire inflation is said to have a greater effect (footprint as well), upon MPG figures than oil weight. Don't get me wrong, I'm not knocking any efforts for increases in efficiency here. Even a lighter weight oil that's not allowed to warm up fully is presenting itself as a heavier weight, and will thus result in lower than average MPG figures.

 

[vronline]

Appreciate the feedback Curious Kid...

 

[Iain]

quote:

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If you want to obsess, obsess about the filter - but that's a different part of the forum...

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Been there, done that. Initial research indicated Wix have the best compromise between flow rate and particle filtration. Follow on research have confirmed that.

quote:

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BTW have you changed the trans. oil, brake fluid, PS fluid, etc? I think these would reward your efforts more than splitting hairs on these 2 excellent oils.

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Yes, I have. These items, PCV valve, fuel filter and spark plugs were all replaced shortly after initial oil change.

quote:

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If you do alot of high rpm driving, stop and go, mostly street driving, etc. go with 5W30 if your manual states it. If not go with 5w20 if manual permits it to do so. 5w20=better mpg. I wouldn't ever mix, just stick to one for what it's worth.

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quote:

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the 3.0 Duratec in my Mazda calls for 5W-20. That's what it gets. No complaints here.

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These are both excellent points as owners manual specifies 5W-20 oil.

Additionally, earlier in the week I went to a local auto supply dealer who had an ample supply of pre-Katrina 5W-20. All 5W-30 oil was post-Katrina. Methinks there is a message there.

 

[JohnnyO]

I would use Mobil 1 5w-20 and not worry about it a bit. Use the 5w-30 in the summer if it makes you feel better. Maybe drop $20 each for two UOA's comparing the two. I think when you buy any used car at least one UOA is money well spent.

 

[Ugly3]

Run 5w20 and forget about the engine oil. Get a great filter (Mobil 1 or Purolator Pure One) and the engine will out last the rest of the car.