Castrol GTX 20w50 , looks like im the only one who likes it thick here. Oil pressure rarely drops below 40psi

 

Im afraid to use 0w30. any reason why to go with 0w30. Right now i use 10w30 mobil 1.

 

There is no reason to be afraid of this particular 0w30, as this oil I'm using is actually thicker than Mobil 1 10w30 at operating temperature, yet it's much thinner in cold weather on a cold startup. So in other words, it's exactly what you want an oil to be! And it does not use much, if any viscosity index improvers, so it does not thin out as you put more miles on it.

Amsoil 0w30 is also similar to this oil, although not quite as thick at operating temp.

 

i cant believe that new german made oil is green in color

 

Pat,

I visit the OilGuy forum a bit, and have been looking at the German Castrol. Any cons to running it in a high compression stroker? I'm running Redline 10w-30 in it now.

 

I used the Mobil 1 15w-50 and the pressure is great now compared to the conventional Castrol 30wt I had in it.

 

cool , Ive sworn by 20w50 for years , been using it in my 84 since I bought it , 190k miles on the original bottom end and it runs better than the day I bought it.

 

I'm curious, if you're running Redline in it, why would you want to switch? You definitely could, as both of those oils have similar viscosities at 100C. And I do believe German Castrol can show wear numbers just as good as Redline.

But truth be told, Amsoil, Redline and German Castrol should all be pretty darn close to each other in terms of engine wear. Which means you could pick your oil based on price and availability. In this regard, German Castrol is defintely cheaper, but may not be as available to you depending on your area. In my area, GC 0w30 is way more available, since it's at all the Walmarts and many Canadian Tire stores, while Amsoil is very hard to get, and Redline is three times the price of GC! (it's $17 a quart up here!!)

 

Don't automatically assume that higher pressure is good though. If your normal oil pressure is super low for instance, due to a worn engine, and then you put in a thick oil and the pressure goes higher, do you think that thicker oil has magically repaired the engine? No, it's simply creating more resistance to flow, therefore you see a higher pressure on the gauge.

Thicker oils can create more engine wear than you think, due to the engine having to work too hard and you could see higher oil temps too. The main thing with a thicker oil though, is that on a cold start it is so incredibly thick that unless you live in an area that sees 100F temps every single day and doesn't go below 70 overnight, it'll just create too much wear. What you want is an oil that will flow incredibly well when cold, and still be relatively thick enough when hot to protect the bearings. Based on my very low levels of lead with the 0w30 Castrol, I'd say this viscosity is just about perfect for a stock or near stock LT1. Obviously if you're engine has been rebuilt to looser clearances, you can then run a slightly thicker oil. So the LT1 likes an oil which is on the thick end of the 30wt range, is basically what I'm saying. The oils which are on the thinner end of that range don't do as well.

 

One more thing with thicker oils. They lull you into a sense of security, since often your engine will sound quieter, mainly because the thicker oil buffers the sound better. So it may appear the engine is running better, but in fact all you're doing is losing MPG and reducing it's horsepower output.

A rough estimate is that if you've got a 300hp engine and you're running 20w50 or 15w50 oil, you're losing about 5hp compared to running a 0w30, 5w30 or 10w30 oil.

I would like to see someone with an LT1 do an oil analysis when running these thick oils though. Actually, I'd like to see any of you do oil analysis, I know many of you are interested in oil, and doing oil analysis on your oil is the best way to help figure out if what you're using is good. It also helps prove that 3k intervals on synthetic are no better than 6k intervals, engine life will be the same either way (so you might as well save money and time by doing 6k intervals!)

 

Okay, i never really got a clear cut answer on my second question. Should I go ahead and switch to Mobile 1 even with that many miles. I do not want to create another problem or a bigger problem but if it's better I'd like to switch.

Thanks

 

For a lot of answers go to; mobil1.com

 

Pat,

The redline is 8 bucks a quart here in Ca. I was just thinking if I could save a little money on the Castrol...why not do it. Not to mention the 0w oil must be a bit better in terms of start-up wear.

I do like the Redline, and have been running it for a couple of years now....but if I can save some loot, all the better.

 

In that case, go for it, as GC 0w30 is $5 per quart or less at Autozone. They just ran a deal on all Syntec oils too, including 0w30, where if you bought 5 you got one free. I know one guy who really took advantage of that special, to add to his huge supply of GC 0w30. He now has 144 quarts of it! I've got a smaller supply of 34L (it was 50L but I just did a bunch of oil changes in my family's cars)

 

I found that interesting, as back in South Africa our Castrol GTX oil is greenish in colour, I always found that interesting too. I have a 88 VW GTI 16V back there and have always used GTX in it and it has over 250000 Km on it and still running strong, not one leak.

Here I normally use valvoline 5W30, but am going to change to Max life now, I have 83K and it now seems be have a little leak.