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Discussion Starter · #1 ·
This has nothing to do with which brand of oil is best for your car but the differences between 30 weight oil and a 40 weight oil. Particularly, the advantages and disadvantages of running one over the other. It seems the only simple conclusion I can reach is the lighter the oil the better the fuel economy while the heavier an oil the greater the protection at higher temperatures. So, if engine protection > fuel economy then I should use a 40 weight oil?
 

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The owners manual should have a good graph of different temps and viscosity recommended.

You will be fine with a 40 weight oil during summer but I would not run that during the winter as the car will be harder to start. I just put 0w30 Mobil one in mine for the winter.
 

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Not really.
40 weight is not necessarily better engine protection.
If you know you run excessively high oil temps, over 275F sustained, then thicker oil may be better. Thinner oils will be pumped at a greater rate and will make more passes through oil cooler and get to part s much quicker on cold starts.
Thicker oil opens the filter bypass and result in a much greater percentage of unfiltered oil.
Thicker oil uses more HP to run oil pump.
Thicker oil with its lesser flow yields higher temps in components where oil cooling is primary cooling like pistons.
Thicker oil is old school. Oil is SO much better than it used to be. Engines are built to much tighter tolerances and thick oil is not needed and will result in a nastier engine on the inside and more crankcase vent accumulation of sludge.

The only good thing I could list that thick oils would do for a non-competition engine's oil is that if you don't drive your car very often and it will sit w/o being run for two weeks or more regularly then thicker oil will maintain a better film on engine parts.
 

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To be fair, I only run 10w30 during the summer. I chose to use the Amsoil dominator racing oil in 10w30 in both the V70r and my modded 300zx twin turbo during the summer.

The Amsoil dominator is a racing product so it has better ZDDP levels than normal oils would.
 

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Discussion Starter · #5 ·
This is true, I always run 0W30 all year round but what I am trying to figure out are the benefits of running a 40 weight oil. I know the heavier the grade of oil the greater it s viscosity, meaning it is less resistant to flowing. The lower the viscosity the eaisier the oil flows. So, in other words, the flowing properties of water versus honey. So why run a higher viscosity oil in the R, are there are particular benefits of running a higher viscosity oil?
 

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There are no benefits if there are no conditions indicating it should be used, only detriments.
 

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To be fair, I only run 10w30 during the summer. I chose to use the Amsoil dominator racing oil in 10w30 in both the V70r and my modded 300zx twin turbo during the summer.

The Amsoil dominator is a racing product so it has better ZDDP levels than normal oils would.

I have been using the 5 w 30 euro blend amsoil and it seems great. Says for turbo cars right on the bottle.
 

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The Amsoil dominator is a racing product so it has better ZDDP levels than normal oils would.
You need to be careful running full racing oils in a street car w/ a catalytic converter. It's the ZDDP that fouls the converters. That's why they dropped the levels of ZDDP in all the "street car" oils back around 2004/ 2005... to save the catalytic converters of newer cars.

I remember a bunch of us in the muscle car community were noticing a ton of flat-tappet cam shaft failures when breaking in freshly rebuilt motors. I paid particular attention because I was just finishing the engine for my Plymouth, and was getting ready for the initial break-in. Nobody was doing anything differently. Even cars already broken in were seeing cam failures. It was found out that the ZDDP levels were dropped, and that the protection needed when breaking in a rebuilt engine just wasn't there. No information was released as to the change in formulas. I believe Comp Cams made the discovery when they noticed all the failures. That's why I was using Rotella T in my Plymouth. Diesel engine oils were not required to reduce their ZDDP levels at that time. Besides, it's really not needed in the newer cars. Newer materials, anti-friction coatings, & roller cams reduce (not eliminate) the need for ZDDP in street applications.
 

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I use 5w-30 all the time....Tho in the summer. boosting under high temperature days i got a low oil light which scared the crap out of me....so i might have to rethink the weight for the summer maybe?
 

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You need to be careful running full racing oils in a street car w/ a catalytic converter. It's the ZDDP that fouls the converters. That's why they dropped the levels of ZDDP in all the "street car" oils back around 2004/ 2005... to save the catalytic converters of newer cars.

I remember a bunch of us in the muscle car community were noticing a ton of flat-tappet cam shaft failures when breaking in freshly rebuilt motors. I paid particular attention because I was just finishing the engine for my Plymouth, and was getting ready for the initial break-in. Nobody was doing anything differently. Even cars already broken in were seeing cam failures. It was found out that the ZDDP levels were dropped, and that the protection needed when breaking in a rebuilt engine just wasn't there. No information was released as to the change in formulas. I believe Comp Cams made the discovery when they noticed all the failures. That's why I was using Rotella T in my Plymouth. Diesel engine oils were not required to reduce their ZDDP levels at that time. Besides, it's really not needed in the newer cars. Newer materials, anti-friction coatings, & roller cams reduce (not eliminate) the need for ZDDP in street applications.
I'm not worried about the cat, it will be replaced soon any ways. This summer it's not getting dominator, I will be running something cheaper. The dominator served its purpose, I missed a shift to fourth and put it in second. The tachometer looked like the picture IPD posted. I'm going to change my driving style, plus some more power from modds won't need to rev out so much.
 

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Discussion Starter · #11 ·
Wouldn't that be great if ZDDP actually clogged your cat? I would be like darn, now I have to get a new downpipe and if im going to spend the money it might as well be a performance oriented one with a high flow cat
 

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Apparently it does. All current engine SM & CJ-4 oils have very low ZDDP levels to counter act (or I guess slow) the affect it has on converters. Only racing oils (labeled as off-road use) now have anything close to the old levels of ZDDP (1200PPM). Even the Diesel oils that I use to run have much lower levels of ZDDP than they use to. I bought 3 cases of GM EOS oil treatment back before they changed the formula in 2005. I got 1 case left. It's what I use to supplement the oil in the Fury. Other good ones are ZDDPlus, & STP Oil Treatment (Red Bottle, not Blue).
 

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I have been using Fuchs Titan GT1 5w40 in the past 2 oil change and I have great result.
The car is more lively than when I was running Castrol Edge 5W30.
A lot of the turbo charged vehicles running thicker oil.
Many STi/Evo owners run 5W40 on their car although factory recommend 5W30 and they have great result too.
Many of them run Shell Rotella T6 5W40
Yes they are label for diesel engines but it works on gasoline engine too
With several additive it provides more protection for turbo charged vehicles.
Some people run it in their light mod or heavily modded 500+hp cars.
One down side is it may cog the cat tho.
Good thing is its very cheap and available in wal-mart.
I am going to give it a try next time.
 

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Discussion Starter · #14 ·
IDK about additives, im currently running motul 0w30 ester based oil right now and it seems really good. However, in a couple thousand miles im switching to redline 5w30. ITs less viscous at operating temperature and has a higher flash point than their own 0w30. On the other hand, i am currently emailing one of the technicians at liqui moly in reagards to their cera tec additive.
 
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