What motor oil is the best?

OK here is my problem. I'm coming up on 10,000 miles soon on my 04 STi. Yes that's original miles on my 04. I have used castrol gtx 10/30 since new and I don't burn one ounce or use any oil. I wanna change over to synthetic and wanna know what you boys think I should switch to. I hear stories that mobile 1 sucks from some and wanna see what's the best for my STi. Thanks guys.

Best is actually a subjective term... It really depends on the application and some oils are better in some situations than others and visa versa. To be completely honest, If you adhere to your regularly scheduled oil changes there is no "Best Oil". Use the right viscosity and grade for the application and change it regularly and you will never go wrong.

The better oils will...
- have a high temperature smoke and flash point
- contain low amounts of ash.
- have good thermal dynamic properties to remove heat from the engine parts.
- contain zinc additives (rare to find because of emissions)
- contain detergents to remove contaminants from the engine parts
- contain polymer strands that won't breakdown to fast. These are usually proprietary from manufacturer to manufacturer so no one is the same.

When your talking synthetic oils, not all synthetics are equal. The higher quality synthetic oils are ester, diester and polyester based oils. They are more durable, contain no ash and have unrivaled thermal properties and a very high smoke point. The disadvantage is that these oils do not mix with conventional oils and should not be use or mixed with any type of mineral oils. RedLine is a synthetic oil that is ester based.

The Polyalphaolefin (PAO) based synthetic oils are worlds better than conventional mineral oils but not as durable as ester based synthetics. The advantage is a better price and the ability to mix with either conventional mineral oils or ester based synthetics.

Best thing to do is to first understand what viscosity oils to use for the application. For instance if you have a built motor chances are you have bearing and pistons installed with looser tolerances for more oil clearance. In this situation the OEM recommended viscosity of 5W-30 is a very bad thing. In this situation you will want something like 15W-40 and even thicker in summer months.

Once you figure that out the rest is up to you but If I was to give my opinion as to the best oil to use that would be an Ester based synthetic oil like RedLine.

I use Val 10-30 which don't mean anything coming from me. But Calvin at cobbtuning Plano (Tuner) uses Pen. Syn. Believe it or not. Lol he said moble one made it and pen. Bought the rights.

Thanks guys for the info. Holycrap I heard redline is top notch stuff and I was leaning toward that cause of what I read about it. I just don't wanna use oil or burn anything cause I don't now.

CRZTRBO said:

Thanks guys for the info. Holycrap I heard redline is top notch stuff and I was leaning toward that cause of what I read about it. I just don't wanna use oil or burn anything cause I don't now.

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That is understandable. When mine is done with breakin I plan on using redline forever (or untill I blow this motor to):rofl:

Some of the most well regarded oil that is easily availible I'd the Shell Rotella T6. I love it as do many. Plus you can buy it at Walmart.

So for another 6 months then right holycrap?

I just changed my oil to royal purple 5w30. With stock motor and exhaust.

An oil that alot of people like is the shell rotella 10w40 because it has a goo amount of the zinc in it. However, this I not too good on catalytic convertors. But If I didn't have cats I would run the shell rotella. Catless dp ftw. Please feel free to flame me on my opinion since I didn't do any actual research, just word of month and other peoples stories.

I run Amsoil 5w30 full synthetic for the last 60k 66k on the car now, and i dont burn 1 drop, I put in 5 qts when i do my change and i run the oil for 6k inter changes, I have been doing some black stone oil reports for the past 4 changes and they tell me that i should run the oil for 7k so i am trying it now...FYI... I have been running the Old OEM black filters since new.. I have 3 more left then i plan on running amsoil filters...

I heard Amsoil is really good also. I'm Gonna go to the parts store today and see what they carry in stock! I would like to run Redline or Amsoil cause I heard them 2 are the best, but that's just what I heard from around the racing scene. I also use the blue filters from Subaru cause the dealer is only 4 miles from my house.

Paul.c said:

So for another 6 months then right holycrap?

I just changed my oil to royal purple 5w30. With stock motor and exhaust.

An oil that alot of people like is the shell rotella 10w40 because it has a goo amount of the zinc in it. However, this I not too good on catalytic convertors. But If I didn't have cats I would run the shell rotella. Catless dp ftw. Please feel free to flame me on my opinion since I didn't do any actual research, just word of month and other peoples stories.

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The new Rotella T6 is fine for cats IIRC.

CRZTRBO said:

I heard Amsoil is really good also. I'm Gonna go to the parts store today and see what they carry in stock! I would like to run Redline or Amsoil cause I heard them 2 are the best, but that's just what I heard from around the racing scene. I also use the blue filters from Subaru cause the dealer is only 4 miles from my house.

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I highly doubt Amsoil will be on the shelf.

Really? Where would I find that?

Go to amsoils website and they have a dealer locator. I might try them next depending on the cost difference between it and royal purple. Or I may just go with shell t6 since Jared has informed me that it is safe on cats. Jared, is it safe on cats or just safer. I know they changed the formula but I also know that they just slightly changed it. What's the word man?

Paul.c said:

Go to amsoils website and they have a dealer locator. I might try them next depending on the cost difference between it and royal purple. Or I may just go with shell t6 since Jared has informed me that it is safe on cats. Jared, is it safe on cats or just safer. I know they changed the formula but I also know that they just slightly changed it. What's the word man?

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The older "T" was marked toward diesel engines only because of the zinc and the wear on cats it was popular for the catless guys. The new T6 is marketed for gas engines and has a new formula. I think a remember reading that the formula revision reduced the zinc. It would make since seeing as how it is marketed for gas engines that are required to have cats. I'd do it with out double checking but you can always confirm this if you'd like.

BAD STI said:

The older "T" was marked toward diesel engines only because of the zinc and the wear on cats it was popular for the catless guys. The new T6 is marketed for gas engines and has a new formula. I think a remember reading that the formula revision reduced the zinc. It would make since seeing as how it is marketed for gas engines that are required to have cats. I'd do it with out double checking but you can always confirm this if you'd like.

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I believe you are correct, it is supposidly OK for cats now. I have been doing some research on it and it seems to be a solid oil. I have been using the new Castrol Edge stuff since it came out and it has been good to me. Now that im catless I think I will switch since there is nothing to worry about anymore. Plus the WalMart by my house had it on sale for 20 bucks/5qt container. Cheap!!!

Well that's cheap compared to all the other oils out there.

Very cheap, I have no Idea how much Red Line is nowadays, but that would be the only specialty oil I would ever consider. But I still don't think its worth the extra $$ for a DD car.

See I'm gonna do track days and auto-cross next year so I just wanna make sure I got the best for it when it comes to protection.

i use mobil 1 5w30 full synthetic in my subi and change it every 3k miles. are you able to just switch to something else? i think i wanna try RedLine now lol.

Yes subi<3babe you should be able to switch over no problem. Do you burn any oil in 3,000 miles? I think I'm going with redline is what I'm gonna do.