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Read our primer articles on High Mileage Oil, Synthetic Oil and Kinematic Viscosity

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I'm not sure about Shell's Rotella prtdvl, but here a few of the "true" synthetics that I know about:

Motul
Royal Purple
Red Line
Amsoil
Neo Synthetics
Synergyn
Torco
Elf
German Castrol (Syntec 0w30, will say made in Germany on the bottle)

Most of these with exception of the last on are considered boutique synthetics, but most of your everyday manufactures do have a synthetic, whether or not it is all Group III, IV, or V basetocks, I do not know. The only one that I'm positive on is Castrol Syntec. This is the oil that took on the system and won, being able to call a Group III basestock "synthetic".

Any body else can chime in with more info now...
Whether a oil is good or not truly depends on how well it performs in your engine. There are many Gp 3 based oils that perform incredibly well.

As for Shell's Rotella-T synthetic oils, they are group 3 based. This does mean that they're made from a severely hydrotreated mineral oil. However, they are classified as a XHVI (extremely high viscosity index) oil and therefore give performance nearly equal to PAO based group 4 products. At this level of refinement the additive package of the lubricant is normally what differentiates one product from another.

Generally speaking, the quality of a gp4 oil is more reliable than is the quality of a gp3 oil. This is because one oil comes from gas molecules and the other oil relies upon mineral crude to provide the base. Not all gp3 oils are equal and this is seen through OEM testing results with different brands of lubes. Why would Castrol's GP3 based 10W-30 pass a sequence test while Valvoline's gp3 based oil wouldn't? It's purely because of the purity of the refined feedstock.

So don't make your oil selection based solely on the basestock of the oil. Mobil-1 makes a very good product and it is gp4 based, but Mobil-1 doesn't always perform the best in every engine. Some instances will show Castrol's gp3 oils perform better than Mobil-1, especially with regard to wear metals in the heat affected areas such as upper cylinder bore regions.

And with regard to Shell Rotella-T 5W-40, in my opinion it is one of the best oils for the price that you can buy.
Thanks Johnny. I can get Rotella Synthetic for roughly 3.50 per quart, whereas Mobil 1 is 5.24. The main reason I wanted to try the Rotella is because they make a 5w-40, and I don't think Mobil 1 does, or at least I can't find it, and I prefer to use 5w-40 rather than the 0w-40 my Mercedes recommends because I've Heard of 0w-40 shearing too much, and more importantly, my Mercedes rattles like a diesel with the 0w-40 in the winter at start up.

I ran the Rotella 5w-40 in my Motorcycle (that often revs to 10-11k RPM) for over 7k miles, and it came out looking close to how I put it in. I know it is said that you can't judge an oil by it's color, but this must say something, when every other oil I've tried in it came out black and near water thin after only 4-5k.

In my truck, oil consumption is down to nearly nothing in 5k miles, whereas with the Mobil 1 it was nearly 3/4 of a quart for 5k miles. I think I'll stick with it.
Personal experience: Mobil1 'burns off' faster than Amsoil ('83 2.7l Chev S-10 ). I don't have any extended experience with Castrol Syntec. During the days of 10,000mi powwertrain warranties I changed to Amsoil in my S-10 at 10k mi, engine, trans(auto), xfer case and both diffs. I changed oil and filter at 20k mi and filter with top-off at 10,000mi. At the 10k interval I may have used 1/3 qt of Amsoil. At the same interval with Mobil1 I would be close to 'add', and much darker than with the Amsoil. At 165k mi I had compression of 158 to 162psi across cylinders with the four cylinders in the middle being within 1lb., no drips, no smoke, 28mpg highway. I recently put Amsoil 0W-30 in my 50k mi 3.0L(mitsu) Dodge Stratus R/T. In the course of the last two weeks my engine seems quiter at idle, I seem to be getting consistently better mileage (+1.25 - +1.75mpg)over Mobil1 (finally ordered Amsoil on-line), and the occasional, almost imperceptable 'twitch' in my tach at idle has gone away I was actually considering plugs, etc. even though it came with platinums for 100k mi(you have to remove part of the intake to reach the back 3 plugs...). I haven't used any of the other 'boutique' synthetics, and given my experience with Amsoil and the long drain intervals I will be using, I'm not inclined to do any switching now.
quote:
Originally posted by airnut:
Personal experience: Mobil1 'burns off' faster than Amsoil ('83 2.7l Chev S-10 ). I don't have any extended experience with Castrol Syntec. During the days of 10,000mi powwertrain warranties I changed to Amsoil in my S-10 at 10k mi, engine, trans(auto), xfer case and both diffs. I changed oil and filter at 20k mi and filter with top-off at 10,000mi. At the 10k interval I may have used 1/3 qt of Amsoil. At the same interval with Mobil1 I would be close to 'add', and much darker than with the Amsoil. At 165k mi I had compression of 158 to 162psi across cylinders with the four cylinders in the middle being within 1lb., no drips, no smoke, 28mpg highway. I recently put Amsoil 0W-30 in my 50k mi 3.0L(mitsu) Dodge Stratus R/T. In the course of the last two weeks my engine seems quiter at idle, I seem to be getting consistently better mileage (+1.25 - +1.75mpg)over Mobil1 (finally ordered Amsoil on-line), and the occasional, almost imperceptable 'twitch' in my tach at idle has gone away I was actually considering plugs, etc. even though it came with platinums for 100k mi(you have to remove part of the intake to reach the back 3 plugs...). I haven't used any of the other 'boutique' synthetics, and given my experience with Amsoil and the long drain intervals I will be using, I'm not inclined to do any switching now.


In 2001 , Mobil totally reformulated their PCMO synthetics . To get a better idea of what you are saying please post the year of the Mobil 1 that you used . Was it 1993 ?
Actually one quart lost in 10k miles is not bad at all for a motor of that design especially when compared to an oil which is prone to oxidative thickening upwards of three centistrokes in the amount of miles .

50wts do tend to seal the rings better than 30wts ... so the experts write on the internet anyway . Smile
Motorbike,
The "S-10" days were 1984-1991. I THINK the oil weights were both 10W-40, maybe both were 5W-40 or 5W-30. The 3.0L Stratus R/T got a change of M1 (0W-40???)"15,000 mi between changes" oil when it became available during the spring/summer of 2005 in prep for a trip to Fl.After the second fill-up I was not happy with the mileage I was getting, seemed to be down 'somewhat'. I went to a tire store to get my wheels re-balanced and had them change the M1 out for (their offering)Valvoline semi-syn 5W-30. 5K mi later in went the Amsoil 0W-30. I had been using M1 5W-30. Since I have been doing recommended-interval changes up to this point with the M1 on a engine in good condition I don't have a long enough time line to compare the Amsoil and new formulation M1 for "bur-off" like I did with my S-10.
quote:
Originally posted by Motorbike:
quote:
Originally posted by airnut:
Personal experience: Mobil1 'burns off' faster than Amsoil ('83 2.7l Chev S-10 ). I don't have any extended experience with Castrol Syntec. During the days of 10,000mi powwertrain warranties I changed to Amsoil in my S-10 at 10k mi, engine, trans(auto), xfer case and both diffs. I changed oil and filter at 20k mi and filter with top-off at 10,000mi. At the 10k interval I may have used 1/3 qt of Amsoil. At the same interval with Mobil1 I would be close to 'add', and much darker than with the Amsoil. At 165k mi I had compression of 158 to 162psi across cylinders with the four cylinders in the middle being within 1lb., no drips, no smoke, 28mpg highway. I recently put Amsoil 0W-30 in my 50k mi 3.0L(mitsu) Dodge Stratus R/T. In the course of the last two weeks my engine seems quiter at idle, I seem to be getting consistently better mileage (+1.25 - +1.75mpg)over Mobil1 (finally ordered Amsoil on-line), and the occasional, almost imperceptable 'twitch' in my tach at idle has gone away I was actually considering plugs, etc. even though it came with platinums for 100k mi(you have to remove part of the intake to reach the back 3 plugs...). I haven't used any of the other 'boutique' synthetics, and given my experience with Amsoil and the long drain intervals I will be using, I'm not inclined to do any switching now.


In 2001 , Mobil totally reformulated their PCMO synthetics . To get a better idea of what you are saying please post the year of the Mobil 1 that you used . Was it 1993 ?
Actually one quart lost in 10k miles is not bad at all for a motor of that design especially when compared to an oil which is prone to oxidative thickening upwards of three centistrokes in the amount of miles .

50wts do tend to seal the rings better than 30wts ... so the experts write on the internet anyway . Smile
"50wts do tend to seal the rings better than 30wts ... so the experts write on the internet anyway "

According to testing by these experts(http://www.iantaylor.org.uk/papers/Additives2001.pdf)using very sophisticated measuring equipment a 5W/20 oil provides a higher oil film thickness under the top ring of a modern 2.0 litre gas engine than 15W/40 and 5W/40 oils.
The article was about ring placement , deposits and oxidative thickening . It speaks of the CAT 1N gas engine and further down about a different diesel engine .

Good article I suppose but was generalized because one piston used an acculumlator groove , others did not and there was no mention of piston ring tension differences between the three but the was speak of ring lift angle " on page 13 . Look at the 50wt .

Ommitance of the accumulator groove and it's function would have helped the article which seems more of a brief than anything .

If testing oil film thickness with 5w-20 testing apples for apples would be best I would think .
quote:
Originally posted by Dad2leia:
I'm not sure about Shell's Rotella prtdvl, but here a few of the "true" synthetics that I know about:

Motul
Royal Purple
Red Line
Amsoil
Neo Synthetics
Synergyn
Torco
Elf
German Castrol (Syntec 0w30, will say made in Germany on the bottle)

Most of these with exception of the last on are considered boutique synthetics, but most of your everyday manufactures do have a synthetic, whether or not it is all Group III, IV, or V basetocks, I do not know. The only one that I'm positive on is Castrol Syntec. This is the oil that took on the system and won, being able to call a Group III basestock "synthetic".

Any body else can chime in with more info now...
maxima maxum4 extra and ultra are true synthetics

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