clarification..

[kylefire5]

I know it has been discussed a millon times. Throught the reaserch I have done I have reached these conclusions. Tell me if I am wrong please.

5w30 (the reccomended oil) is a little thin and let oil slip by the turbo seals. The reason it is 5w30 is to meet the fuel economy requiments for the US. Where as in other countries the recomended oil is 5w40 a thicker oil preventing the leak in the turbo. This problem is noticeable when a test pipe is installed and smoke is seen because the lack of 1of 2 catalyic convertes. If I were to switch to 5w40 this woudl be healthier for the car and allow the removal of a catalytic converter without causing smoke. Therefore freeing up the exhaust system and allowing the more effiecient performance of the engine and turbo.

Like I said please correct me if I am misled.

Thanks, Kyle

 

[Marauder.45]

I'm interested in the answer too.

 

[Atreyu3388]

You're on the right track. I have switched to 5w40 and am currently running an open Down Pipe and have noticed no smoking problems at all. If you are concerned about modifications affecting the performance/smoking issues with your turbo, pick up a used k04 and send it to Ken at PG for a rebuild.

That's what I'm planning on doing anyways. This year rebuilt k04, next year forged short block w/GT35R.

 

[kylefire5]

Your right I dont want to have smoking issues. I just want the mods that I do to keep the car health and reliable...not really push it when it is not needed. It seems to me that the 5w30 being reccomended here and the 5w40 in Europe is kinda fishy. If the reason the second cat is there is to fix the smoke from that then I want it out and to run 5w40.

A rebuilt turbo would be nice in the future..maybe sooner than later!

 

[Super Shredder]

what are some accessable brands with these specs, i am running Mobil15w30 synthetic right now, but would like to upgrade to 40 now that my turbo is getting older.

 

[GoFast]

You are correct in saying that it has been discussed a million times and after a quick search and read through, I think switching oil is the wrong approach to this. A catch can is the better approach IMO. Here is one thread(out of a million) that sums it up in just a couple pages. http://www.mazdas247.com/forum/showthread.php?t=123740298&highlight=5w40

There are other threads that I havent read through but I would imagine they would conclude the same.

 

[Blendercloud]

GoFast is right. If you are having smoking issues using 5w30 after removing the 2nd catalytic converter, then you need to have the turbo seals replaced. You should continue to use 5w30 unless having those seals replaced is completely out of the question.

You will see a minor power decrease, probably 1.5-2% from increased resistance within the engine as well as a drop in fuel economy of as much as 15%. Will it hurt the engine? No, but it will affect the engine's efficiency and performance.

SS, a lot of folks have discussed Mobil1 synthetics as not being as great as the next. I don't know specifics, but I know that Castrol has always worked really well for me. BMW recommended it for my 3-series and I've used it ever since without any issue at all. I think if you're going with one of the big brands, Castrol, Mobil, Quaker State, Pennzoil, etc. you are on the right track and probably can't go wrong. Royal Purple is also an option.

 

[kylefire5]

thanks

that is kinda what I needed everyone has their own opinion os this subject. I wish there were a definitive answer. This is close! I will proly stick to a 5w30 synthetic and go to a catch can from there if I notice smoke problems.

Thanks, Kyle

 

[Blendercloud]

Glad we could help! Good luck.

 

[GoFast]

the difference between the two is that switching to thicker oil is more of a band aid approach and the catch can is more of a real fix.

 

[kylefire5]

Makes sense. I appreciate the input. I just want to do what is best for the car. The thing that threw me was the different recomendation in other countries.

 

[bova80]

GoFast is right. If you are having smoking issues using 5w30 after removing the 2nd catalytic converter, then you need to have the turbo seals replaced. You should continue to use 5w30 unless having those seals replaced is completely out of the question.

You will see a minor power decrease, probably 1.5-2% from increased resistance within the engine as well as a drop in fuel economy of as much as 15%. Will it hurt the engine? No, but it will affect the engine's efficiency and performance.

SS, a lot of folks have discussed Mobil1 synthetics as not being as great as the next. I don't know specifics, but I know that Castrol has always worked really well for me. BMW recommended it for my 3-series and I've used it ever since without any issue at all. I think if you're going with one of the big brands, Castrol, Mobil, Quaker State, Pennzoil, etc. you are on the right track and probably can't go wrong. Royal Purple is also an option.

this is not true. a 5w40 will not hurt the engine, its actually better for these engines due to the heat from the turbo and fuel dilution we experience. i have a uoa on my amsoil euro 5w40 and it was really good and i'll be doing another one on my rotell t-syn 5w40. there is more to the smoking turbo then just leaking turbo seals. if that was the case why did mine smoke last summer but now that i use 5w40 oil, use oil catch can, and also increased my idle rpm to 900 does it not smoke and hasn't smoked once for over 6000 miles?

i will say it did smoke once with 5w40 when i had already had 5.5qts of oil in and decided to add just a little more after having 1500 miles on the oil, it smoked for about 2 weeks here and there until that oil was burnt off. so overfilling this car can also lead to smoking.

trust me on this i've researched the issue for 6 months after it first happened to me because i wanted to have a downpipe again and now i do.

there are plenty of people that got new turbos from the dealer only to have them smoke as well shortly after. also make sure your dealer doesn't put in 5w20 because that has happened more time than not. oh and i think a few UOA's have proven that mobile 1 isn't that great of an oil. i'd going with amsoil or the shell rotella t-syn i'm using now.

 

[blackwidow]

+1 .

 

[bova80]

i'll also elaborate on why other countries have the different oil recommendations. its because here in the US we have strict CAFE standards so to meet that they recommend only 5w30, where as other countries who aren't so uptight can recommend the other oil weights. after talking to a tuner he said to use a 5w40 or 10w50.