I just did my first Amsoil oil change after 4500 miles of using Amsoil Series2000 0-30 - top synthetic oil from Amsoil.
It really did not feel like it can last 35K miles/1 year, after 4500 miles of driving in Florida's heat with A/C on and heavy traffic many many times, engine started to feel heavy, more harsh and reving was not as smooth as before.
It was asking for oil change, I looked at the oil dip stick and that Amsoil looked almost black!!!
How can it last 35K???
It is a great oil, better than Mobil1 and many other synthetics out there, but I just can't imagine how it can last 35K miles or 1 year (which ever comes first).
Don't get me wrong, it's a great oil.
Performance-wise it really smoothened out cold starts and it rev's much easier, engine operates smoother and there is less vibration from the engine.
Just my observation.

 

Going 35K on an oil change is not something everyone can do and is something that's not really explained very well on their website.

Some factors in having a drain interval that long are the oil filters that should be changed every 12,500, if they are Amsoil's, or Mazda's standard interval if any other filter is used. The filter is a critical part of the equation. Besides Amsoil's own filter, Mobil 1's is an excellent choice. Cheap filters like Fram should be avoided, their paper media breaks down very easily with heat and use and not last very long. The car should also be used mostly for highway trips and whenever it is started should be warmed up fully before shutting it off. The more short trips you do, the shorter your interval shoulbe be.

Color is not really an indications of whether the oil is still serviceable or not. Part of the reason your oil might be turning blacker than you expect is that it is cleaning a lot of the gunk left behind from the conventional oil. I don't know the mileage of your car or how long it's been running synthetic oil, so I can only guess. The only way to truly tell if the oil is worn out is through an oil analysis program. I personally wouldn't feel comfortable extending the drain intervals to 35K without these results, as every car, environment and driver is different.

I track my car on roadcourses, so it sees some pretty extreme conditions. I use 5W-30 in it. I ran Mobil 1 and Amsoil for 8K miles apiece and had the results analyzed. The Mobil showed signs of being "stressed" but the results on the Amsoil indicated that it had many many more miles left. I have seen analysis results from daily driver cars with 15K on them with Amsoil in the crankcase that came back with the comment that the oil was still safely serviceable.

If you're really worried about leaving the oil in for a longer period of time, sending a sample out for analysis can be a great way to ease your mind.

 

Sorry for a long time no response and thanks for a detailed answer.
Filter used was Pure One - Purolator.
Should I notice engine/transmission performance decrease?
Most of the time after 3-4K I can feel that the engine/tranny is not working as smooth/quiet as when oil was new and to me it's the first sign that oil should be changed.
Tranny (auto) is also not shifting as quickly and firmly as it does with new oil, it stays up for too long before down shifting.

My P5 takes only 3.25 quarts of oil, I would much rather change it
every 3-4K miles and maybe switch to Amsoil 5-30 XL7500 series or maybe .... try new Mobil 1.
Series 2000 cost is $9, and M1/XL 7500 is around $5 per quart.
What would you do?

 

i recently switched to amsoil and am not able to tell the difference from before. i was previously using mobil 1 10w30, and the amsoil seems to perform the same in smoothness and power at the track. im waiting to see if it will outlast mobil 1 and be worth my extra 2$ per liter. does anyone know anything about the differences between mobil 1 and amsoil?

 

There shouldn't be any engine/transmisison performance decrease, in fact it should be the opposite. I'm not sure how many miles your car has on it now, but the louder engine may be a result of the breakin process. I'm just speculating in this case, though. The age of the oil should not really affect how the transmission shifts either, so that's an interesting case. Am I reading the post right, after changing the engine oil the transmission downshifts faster?

As for my recommendation on which oil, I personally prefer the full synthetic 5W-30 over the 0W-30, primarily because of cost reasons. Their are actually two different 5W-30's, the full synthetic and the XL-7500. I tend to stay away from the XL-7500 because the price difference is miniscule in these two oils, and the full synthetic is a much better oil. The 5W-30 is comparable in price to Mobil 1 as well.

As for filters, the PURE One filter is not the best out there. Mobil 1 is actually the best readily available filter for people who don't use Amsoil's. Mazda's is really good as well.

I have a standing offer for 15% off retail prices on most Amsoil products for members here. Feel free to email me through this site or my website for more information if you're interested.

 

In terms of "feel", there really aren't any noticeable differences bewteen Mobil 1 and Amsoil. The primary differences come in the additive packages inherent in the oil. Amsoil holds up much better to abuse and to long term use than Mobil will. Amsoil is also much less volatile, by almost half, which leads to reduced oil consumption and reduced emissions. The volatility is one of the main reasons that Amsoil holds up better under high temperature use and is better able to protect your engine than Mobil can.

Deciding if it's worth the extra $2/liter depends on your priorities and how you drive and maintain the car. There isn't an answer set in stone, as much as I wish there was