Amsoil here with high zinc

 

I've been using Mobil 5W-50 since I got my car. Napa actually has it in some stores-I've also ordered online rom ECS, $7-8 on sale from time to time. Castrol 5W-50 is not on the P approved list

 

Ok, how about some discussion about oil pressure. In my '07S, I ran 5-40 Redline, an oil I have used in my several cars for over a decade, various viscosities, depending on what the manufacturer recommends. I live in Upstate SC, and it gets hot here in the summer, occasionally 100 degrees or so. In my prior S Porsche, my oil pressure on a hot day at "cruise" would run at 4 bars, oil temp 215, if i was in traffic and running in second gear a lot with RPM, it would drop a little when the oil temps would crawl up to 230. I was going to switch to 20-50, but sold the car to get our present '07 GT3.

Our GT3 came with all maintenance records since new, and was last filled with 0-40 M1. It pegs the oil pressure gage with any RPM over about 2K, at hot idle, around 2 Bar, ie, 30 psi. Right now the car is at Zuffenhause up near Charlotte, for the pipe weld with BBI inserts (they machined off the sharp hose retention nibs). I left a case of RedLine 5-40 to re-fill the engine with them. Most modern engines have an oil pressure relief valve, I think the latest Porsche engines even electronically adjust the oil pressure depending on need.

So while a higher viscosity oil may offer a more stout oil film at bearing surfaces, for our car it won't give a higher oil pressure. What oil pressures with what oils are the rest of you getting on your cars?

All the best...

 

Thanks for posting these up. It was interesting to look at the other numbers beyond the usual suspects like Zinc that the eye usually zooms in on. I'm not a chemist but it doesn't mean I can't have fun looking.

It was interesting to see the calcium in the mobil was much higher than the other two. I understand it is in there as a detergent, and the comments by the lab at the top of the Rotella sheet suggest the same. I recently read an SAE paper on the effects of calcium detergent additives on abnormal ignition - http://papers.sae.org/2014-32-0092/. The tests were on supercharged DI engines but was interesting reading nonetheless.

The others seem to use magnesium as their detergent additive. This is also interesting as other papers have shown the tendency of magnesium additives to form crystals leading to filter clogging when moisture and fuel added to the oil. Magnesium was also found to be responsible for deposits and wear in the upper cylinder on diesel engines in testing. I was under the impression that it had been reduced by most oil companies in favour of alternatives like calcium however advances in magnesium compounds may have offset these earlier findings.

Taking the two options together in light of the sheets provided makes for an interesting view. Clearly oil formulation doesn't stand still but also neither does engine requirements. I often wonder how often changes to formulation cure one issue while creating another and how much changes to formulation are driven by the changing conditions within new engines. Where should one stick if either is the case?
Would mobil tested in 2013 read the same as the mobil sheet shown or would it be more in line with the others?
Are the magnesium based additives better out right; are they only better if you have an engine with conditions that caused the abnormal ignition with calcium additives?
Every new bit of info seems to lead to more questions on the oil front. It is all a mystery to me despite my best efforts.

 

My TT always had Mobile 5-40 from Dealer.. That was when I lived in North Carolina.. Since moving and now owing GT3... Had engine out and service done. Dealer serviced with Amsoil 5-40.. Seems like a good options. I run Redline in my ****box racer Miata..

 

Mobil 1 5W-50 on my tops ups and 5W-40 or 0W-40 on winter changes, both the A40 recommended Porsche oil by Mobil 1