"I'll try to show some comparisons using Mobil 1 tech numbers versus the Amsoil ones. I used those that included the same test parameters, but did have to compare their 15W-50 to Amsoil 20W-50. Their numbers are actually pretty good and Mobil is one of the better oils out there, but there are some differences I'll mention at the end:
Viscometrics 40 degrees C cSt
- The lower the number, the better because it means better flow at low temperatures. This is important for the many in colder climates:
Mobil 1 0W-30.....52.0
Amsoil Series 2000 0W-30....57.9
Mobil 1 5W-30.....53.0
Amsoil XL-7500 5W-30....58.4
Mobil 1 10W-30....59.0
Amsoil XL-7500 10W-30....58.4
Mobil 1 15W-50....120.0
Amsoil Series 2000 20W-50....131.8
Mobil seems to do a bit better in this area a bit, with the exception of the Amsoil XL-7500 10W-30. As can be expected, their 15W-50 would have a better number, being a bit thinner than the Amsoil's 20W-50, but not that much different.
- The higher the number, the less change due to temperature.
Mobil 1 0W-30.....176
Amsoil Series 2000 0W-30....188
Mobil 1 5W-30.....162
Amsoil XL-7500 5W-30....160
Mobil 1 10W-30....147
Amsoil XL-7500 10W-30....148
Mobil 1 15W-50....160
Amsoil Series 2000 20W-50....155
This shows that through the change in the oil at various temperatures and how stable it remains at what it should be. While the above numbers shows Mobil intially doing better under cold conditions, how stable do those numbers remain?
- Again for those of you in colder climates. This is the temp that the oil will still pour at.
Mobil 1 0W-30.....-65 F
Amsoil Series 2000 0W-30....<-76 F
Mobil 1 5W-30.....-65 F
Amsoil XL-7500 5W-30....-60 F
Amsoil 5W-30......-60 F
Mobil 1 10W-30....-65 F
Amsoil XL-7500 10W-30....-54 F
Amsoil 10W-30.....-60 F
Mobil 1 15W-50....-55 F
Amsoil 20W-50.....-33 F
Amsoil Series 2000 20W-50....-47 F
Again, Mobil does well in this area with the exception of Amsoil Series 2000 0W-30 that blows them away. And again, as can be expocted, the thinner Mobil 15W-40 does better.
- The higher, the better able to withstand high temperature. This is important, especially with the heat our turbos put out, or if going to the track and running hot.
Mobil 1 0W-30.....460 F
Amsoil Series 2000 0W-30....460 F
Mobil 1 5W-30.....455 F
Amsoil XL-7500 5W-30....464 F
Amsoil 5W-30......442 F
Mobil 1 10W-30....470 F
Amsoil XL-7500 10W-30....471 F
Amsoil 10W-30.....446 F
Mobil 1 15W-50....473 F
Amsoil 20W-50.....457 F
Amsoil Series 2000 20W-50....474 F
Total Base Number (TBN)
- This is basically the additive package that keeps the oil alive and allows it to last longer. The higher the number the better. Most of these numbers for Amsoil are the minimum they allow, usually the numbers I've seen are between 12 and 13! Mobil doesn't list these. From information I have been told, they average around 9 with the excpetion of their Delvac diesel oil.
Mobil 1 0W-30.....9?
Amsoil Series 2000 0W-30....11.4
Mobil 1 5W-30.....9?
Amsoil XL-7500 5W-30....9
Mobil 1 10W-30....9?
Amsoil XL-7500 10W-30....9
Mobil 1 15W-50....9?
Amsoil Series 2000 20W-50....12
Because of Amsoil's higher TBN number, this is one reason that they are able to promote extended drain intervals. The XL-7500 series is their intro line with recommended drain of 7500 miles. With the exception of the 20W-50s, the other oils have a drain interval of 25,000 miles or one year (35K with the Series 2000 0W-30). Of course this drain is lower in a turbo car, but will remain much more stable. Mobil 1 recommends drains according to the manufacturer recommended intervals. This can get expensive every 3000 miles to pour in five quarts of $4+ oil, when for under $6 you can get nearly any of the other Amsoil oils (except the Series 2000) and get many more miles between drains. You can run Mobil longer, it has been done, but they won't warranty it should something happen; Amsoil will for their recommended drain.
I have been told the Amsoil XL-7500 is the nearest to Mobil 1. While some of the other Amsoil may not beat Mobil in all the catagories listed, they do perform better and offer better protection. The Series 2000 has nothing like it in it's class. The more abuse you give this oil, the better it performs. Those of you who like chemistry will like this next part. A petroleum molecule would resemble a single strand with legs coming off of one side. A synthetic molecule has the single strand, but legs on both sides. This is basically why a synthetic is able to withstand about twice the temperature a petroleum can. But the Series 2000 has two strands with legs connecting them, like a ladder, then twisted. This makes it even more durable, but as it gets submitted to extremes, this molecules curls up until the two ends join, making a ring and an even tougher molecule. This is how it was explained to me, and no one else on the market has this type of technology in their oil.
Sadly, it looks like Mobil 1 might have gone the route of Castrol Syntec and has started using a blend of PAO and hyrdo-cracked petroleum oil rather than a straight POA basestock like before. Some of you may recall that Mobil sued Castrol when they changed their formula to this petroleum base and ended up loosing with the ruling being in favor of Castrol and other companies to be able to call this hydrocracked process oil a synthetic. This case was brought out in an issue of Hart's Lubricants World back in the fall of 1999. Now in a follow up article this past fall on companies now going to hydrocracked oils, they said Mobil had as well. Rumours I have gotten is that this may be the Tri-Synthetic. Because of this, I've heard of other people leaning away from Mobil like they did to Syntec. Why pay the money for a product containing petroleum? Mobil was always closest to Amsoil in the past in the Four Ball Wear Test, but as can be seen in the graphs below comparing the Amsoil Series 2000 oils, other brands have now passed them up. I don't know for a fact Tri-Synthetic contains hydrocracked oil, but sources who have talked more with others have said this to be so. And knowing that Mobil has gone that route to some point as a fact, and seeing these newer test numbers does make you wonder."