oil 101

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Dec 20, 2002
The coal hills of eastern PA
I have a brand new vehicle that recommends 5W30. I am reluctant to use synthetics because of their $4+ price. Our local Walmart sells Mobil 1 ss 10W30 at $3.58/quart(other grades are higher). At 10 degrees F, which oil would perform better: a conventional 5W30 or Mobil 1 10W30? As long as I am not increasing start-up wear, I'm going to go against the vehicle recommendations and use Mobil 1 10W30. Opinions anyone?

What is the shelf life of synthetic oil? If I purchased a quart of oil a year ago, how would it compare to the quart I would buy today if the oil was exactly similar (additives, etc.)?

In this order, these are the best in cold weather.
0w,5w,10w -30wt. oils. Mobil 1 is the best oil you can buy on the shelf at a auto store. You don't have to use a 10w if you dont want to. Go with a 0w or 5w for the winter then switch back to a 10w in the summer. People on this board will tell you to run an analysis before stretching the interval change but a good generalization would 3K more then what the manufacture calls for. EX. 3,000 under severe service or 6,000 highway miles you could probably run Mobil 1 for 5-10k miles. Also check Amsoil. It is basically a fine tuned Mobil 1 with a long drain additive package and can go a little longer. At the price you mentioned, thats not bad at all. Oil is cheap, engines are not.

[ December 26, 2002, 07:31 PM: Message edited by: buster ]
If you look at the cold weather specs on 10w30 Mobil 1, it's clearly better than just about every single 5w30 petroleum oil out there.

As far as shelf life goes, an oil is good for about 4-5 years.
I think the container for Mobil 1 10w30 said it pours freely at -49 degrees. Then on the M1 website I think they said most conventional oils become solid around -30 or so degrees. Mobil 1 10w30 will still be better for cold start ups than dino 5w30.

The only reason I wanted to use Mobil 1 SS 10W30 was to take advantage of the great price ($3.58/quart).


That's the information I was looking for. I didn't know how a conventional 5w30 compared to a synthetic 10W30.
Sorry, i didnt read the conventional part. Yes, any Mobil synthetic will flow much lower temps then a dino oil. No comparison.
As was mentioned, M1 10w30 flows at -49F, while Castrol GTX 5w30 (which I feel to be one of the better off the shelf dino oils) has a pour point of only -27F.
Only -27F? Thats good considering it is a dino but it's definitely not as good as M1.

[ December 26, 2002, 09:38 PM: Message edited by: buster ]
Does the cost matter that much? How many times a year do you need to change your oil in that car?...twice a year?

How about Mobil 1 0W-30 or 5W-30 for your Fall/Winter oil change, and Mobil 1 10W-30 or Mobil DriveClean 10W-30 (to save money) for your Spring/Summer oil change. If you average the 0W-30 and 10W-30, you will be using 5W-30, so everything's OK, isn't it?

In any case, tell us more...what car and engine, what oil drain interval requirements, how low will the winter temps be? Zero?...one decision. Minus 40?...different decision. How long is your daily drive...oil completely warmed up or not a long enough drive?


[ December 26, 2002, 10:24 PM: Message edited by: Ken2 ]

The car is a 2003 Saturn with the 2.2L engine. We average 20K miles per year with planned 5500-6000 mile drain interval (6000 max recommended by Saturn) on synthetic lube. I wouldn't feel comfortable stetching a conventional oil past 3K-4K miles before changing. 15 miles one way to work. Temperatures down to 0. At $3.58 (Mobil 1 SS 10W30) a quart I figured I could double my drain interval (to 6000 miles) with synthetic lube compared to dino oil. Money actually is a big issue but I figure its about the same cost to use synthetic for 6k miles (at $3.58/qt.) compared to conventional at 3k or 4K. Also the price for the cheapest oil filter for this car is $8.50 (NAPA) so changing every 6K with synthetic saves me money there also (compared to changing a filter every 3 or 4K miles).
Also, how long do you plan on owning this car?...turn it in at the end of a 3-year lease, or keep running it 'til the wheels fall off?

Is this one of the Saturn engines that develops carbon in the ring grooves which results in a high rate of oil burning?

With a minimum of zero °F and your mileage, I think I'd use three or four Mobil 1 10W-30 oil changes yearly, although I'd feel better with 5W-30 in the winter. Keep looking at Wal*Mart's prices for a deal on M1 5W-30, and buy it whenever you see it cheap.

Mobil 1 10w30 will flow better at low temperatures than any conventional 5w30. Don't look at the pour point, look at the cold cranking viscosity.
$3.58 a qrt for Mobil1 10w30! Thats a smokin' deal. I thought I had a deal buying the 5qrt jug of M1 10w30 @ $17.88 + tax = $19.25 which is $3.85 a qrt. Qrt bottles are $4.70 at Walmart here.

Anyone know what quality blend 5w30 Walmart carries that he might use instead of a full syn since price is a factor? Pennzoil?
no, the 2.2L is not an engine with oil ring problems. The 1.9L is that engine. The 2.2L engine is GM's ecotec that is across the board for gm's cars nowadays. It's a very solid engine.


Originally posted by buster:
Only -27F? Thats good considering it is a dino but it's definitely not as good as M1.

I don't think a pour point of -27 is impressive at all, because that puts it's borderline pumping temperature at about -7F. Meaning a lot of areas of the country get cold enough to put a car running 5w30 dino oil out of commission.

Pour Pumpability Cold Cold

Oil Point Limit Pumping cP Cranking cP

-------- ----- ----------- ----------- -----------

M1 10W30 -49f -42f 10250@-22f 3848@-13f

GTX 5W30 -27f NA 60000@-13f pre>

Is it possible cold cranking converges at like temps? Otherwise M1 10W30 is daddy.


Originally posted by XHVI:
Mobil 1 10w30 will flow better at low temperatures than any conventional 5w30. Don't look at the pour point, look at the cold cranking viscosity.

Correct ! Or the Crank pressures

Phillips 10/40 has a lower pour point than the 5/30 GTX,the Phillips Cp is 4600 for their 5/30
The Mobil Drive Clean Blend 5/30 is 5000 the 5/30 Drive Clean is 5500

Thats the new Ecotec motor in the Saturn,it is a 5 quart system,it should be a bit easier on oil,,should be I said
10/30 motor oil is allowed per the owners manual if the ambient is up

Have you seen the specs for the Pennzoil 5/20 on their website? Looks the same cold weather performance as the 5/30 unless a website error. But the VI at 40 and 100 c is much lower so it must be pumping better

This is NOT a lease vehicle and we will drive it until it dies!


I think one of the reasons that the price is so low is that there isn't much of a demand for Mobil 1 10W30 since the majority of manufacturers recommend 5W30 or lower now-a-days.
I think the manufacturers scared people into believing that is all you could put into your car. Our local Wal-mart has had this price for the last year and the shelves are always full of cases of Mobil 10W30 (that's fine with me!)
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