Royal Purple turns to regular amber after about 2 hours of driving.... If you looked at my oil now it looks like regular old oil.....

I have used both Mobile 1 and Royal Purple, and don't notice a difference, other than the RP has been cheaper lately.....

I don't see the point of running 5w-30 instead of 10w-30, cause at all temps above 45* they are very similar if not the same viscosity, and Id rather have the 10w(thicker) protection in the freezing temps than the 5w(thinner)(a good oil will leave a film, and 5 or 10 should arrive at the same time once the engine is turning)

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2002 GT...Wizardair, ZZP 2.5 o/r dp, Special Eddition two-tone leather interior added, HUD added, 12" Brake Upgrade, ZZP strut tower bars, gmpp sway bars,-6an braided SS fuel hoses , Hptuned, Top Swaped.....
I've got Boost!! I've got only 1.5* KR left my poor L36 block.....

The 5W and 10W is not a measure of thickness of the motor oil. A 5W-30 and 10W-30 are both 30 weight oils. What the 5W and 10W indicate is the so called 'winter number'. It is an indication of a motor oils resistance to flow in winter. A 5W motor oil will begin to flow sooner than a 10W motor oil.

Not sure if that is what you were trying to point out but there is no thickness or viscosity difference between a 5W-30 and 10W-30. They are both 30 weight oils. Where they differ is in their initial start up flow in cold temps and shear stability in the summer temps.

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Scotty Hall
Bartlesville, OK
2001 Pontiac Grand Prix GTP
It whines a lot, but I like it.

The only limitation you will ever face in life is yourself!

GM says put in 5w-30, so I use 5w-30. It performs the same at all other temps as 10w-30, but I'd rather get the oil sooner in the winter than trust a film.

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2004 Impala LS - got some mods
NAIOA Moderator

Making you think twice before picking on Impalas

Yeah, sorry, that is what I was trying to say, the viscosity of the oil is similar if not the same at all temps above 50 - 60* F...I mean yes 5w will flow better at 0* than 10w will, but at that temp the 10 will offer more protection(once it gets there) my GP says 10w-30 on the cap, and I have ran that since day one, not beating the crap out of your engine when it is just started/cold will help a lot more than the 5 viscosity difference that your engine runs in for a total of a few minutes a year(engines get warm quick)


********Above is my opinion, oil is more of a personal preference thing anyway, I knew a guy that still ran straight 30 weight well into the 90's and never saw a problem from it. So make you own decision, above was just my .02

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2002 GT...Wizardair, ZZP 2.5 o/r dp, Special Eddition two-tone leather interior added, HUD added, 12" Brake Upgrade, ZZP strut tower bars, gmpp sway bars,-6an braided SS fuel hoses , Hptuned, Top Swaped.....
I've got Boost!! I've got only 1.5* KR left my poor L36 block.....

The newer GP's call for 5W-30. Not knowing this I brought only 10W-30 with me to Branson, but you can run the 10W-30 even if it calls for 5W-30. The 10W-30 is more shear stable and doesnt break down quite as easily, particularly in summer heat.

That all said, you are correct in that a lot of it is opinion. However, if you can compare apples to apples, then that can alleviate that problem at least on a statistical level. After which, you then have to find the product that works best with your particular engine. You could buy two GP's made on the same day successively on the line and drive them in identical ways and environment and one will work better on one than and the other may take something completely different to get wear numbers at the same level. Which is one of the reasons I am such a big fan of oil analysis. It allows you to tailor products and change intervals to your engine and driving style to achieve the lowest wear numbers and thus the longest life and lowest maintenance costs.

Probably three to four months before my GP puked its differential I had switch over to Amsoils 30W/10W-30 motor oil. It is a diesel engine oil that is formulated to work in gasoline engines as well. It is basically a straight 30 weight motor oil that meets/exceeds the requirements for the 10W-30 rating also. And since it has absolutely no viscosity improvers (as all other multi-viscosity oils do) it has virtually no viscosity break down or shear.

I will be really glad to get my GP back on the road to get some more data from that product as it was doing wonderfully before I had to deadline the GP.

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Scotty Hall
Bartlesville, OK
2001 Pontiac Grand Prix GTP
It whines a lot, but I like it.

The only limitation you will ever face in life is yourself!

Where can i buy amsoil at? Dose any auto part store carry that anymore. I havent heard of it in a while. How much can i get a case of it for from you SyntheticShield.

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=DOHNER=
SILVER 2002 GT

I have heard great things about both. Ive seen some engines last way longer then they should ever have using Mobile 1 Synthetic. That's what I use, so I vote Mobile 1.

Also, you could think about it this way too, when trying to compare 2 brands think about which one may be more readily available. Mobile 1 can always be found at your local Walmart <---and probably cheaper than anywhere else. I personally don't even know where to get Royal Purple. Either way, both are very good oils to use.

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3.4", 3" cated DP, SLP Air box, TB spacer, 180* Thermo, "Bilemke Tuning".

Depends on where you are I guess. Here, everywhere has RP. Even the little automotive section in the base shoppette has it.

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2004 Impala LS - got some mods
NAIOA Moderator

Making you think twice before picking on Impalas

I just did a royal purple oil change with a full quart of lucas stabilizer and k&n oil filter for around 5o bucks...my car seems to like it better than a average synthetic ( i got my royal p at oreillys auto parts) expect to pay over 7 bucks a quart

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160 thermo,pcm,thrasher cai,flowmaster cb ubend delete 3 in D.P.,Fbody brakes,slotted rotors,1/2in trans pan,frnt and rear tower supports,complete audio swap.so far....

What is the lucas stabilizer for, high miles or what?

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=DOHNER=
SILVER 2002 GT