Royal Purple

the 10W or 5W is the lower temperature range, during summer and down south, you can always use 10W I would never -20, too light, always a -30 normal synthetic is OK, M1 etc.

checkout

That pretty much cleared it up for me. I appreciate it.

The oil needs to be thick enough to maintain proper pressure in the normal operating conditions. That's a pretty broad statement that means use whatever gets the job done. To low of viscosity, and you'll score the bearings. Too high, and you waste a lot of energy moving it around, and nit won't oil well at low temps. Let the owners manual and current operations decide the weight. 0W-20 is perfect for my wife's '01 Cougar. But it's a terrible choice for my Ford stroker V8. Synthetic oils and dino oils have essentially the same viscosity properties. Whatever "weight" oil you're using now (assuming you have correct pressure now) should be the same when you switch to synthetics.

I wouldn't but if you insist I'd use the 10-30. Watch the pressure carefully and change the filter as soon as it spikes. RP seems to make a big mess in the bottom of some engines.

Are you switching from dino oil to synthetic? If you are, be prepared to patch a bunch of leaks. I have heard this before and here is written info

. Scroll down to the page where the guy talks about his 911.

My '71 four venturi Cleveland was using 10W40. We recently switched to a 20W40. When I emailed Castrol's website, they recommended 20W50 based on the info I had given them about the engine, driving habits and climate. That may have something to do with the 10.7:1 compression ratio. The oil pressure was actually ~20% higher with the 10W40.

mike

The owners manual states to use SAE 5W-30, or a synthetic brand with the same viscosity would be fine also. Castrols website also says to use 5W-20 based on the miles and driving conditions. The previous owner used 5W-30 castrol syntec, but I have yet to change the oil because I have only owned it for a few weeks.

When I had a 60 chevie that burned oil I would put in the thick stuff, it burns slower to save money. But the thick stuff in a good engine is temporary.

There is a lot of incorrect information on that page and I have know many people to switch to synthetic at a high millage and not have any leaks.

OMG. Be prepared to flush the engine and crank case within the next

8K miles if you switch from Syntec to Royal Purple. I say that from personal experience.

On May 26, 5:48 pm, WindsorFox wrote: Be prepared to flush the engine and crank case within the next

I guess curiosity killed the cat, but hopefully not the Mustang....... Okay, I gotta ask. What happened in your case....sludge? oil separation? Obviously you had to flush it to get some crap out or what? Please elaborate.

Not saying the engine will leak, but what if it does. This is not first time I have heard of this issue.

What other incorrect info did you find as the article is 19 pages printed. I am just looking for more information. Oil could be considered a critical component of your engine. Once you discover you are using the wrong oil, it is too late. My owner's manual recommends "Ford 6000 mile engine oil" and it is difficult find.

I've switched three high mileage vehicles to synthetic. One didn't develop any leaks, one developed a very very slight leak, and the other developed a major leak which was fixed with new valve cover gaskets.

Using Castrol Syntec as apparently similar to using the old Pennzoil, it left the non wear surfaces in my Mustang coated with a thick film that resembled varnish. Keep in mind I did not know this at the time. I changed the oil when I got it with the same Syntec my friend used since the first change. My next change in 3 months was to Royal Purple. The car had ~58K miles on it, mostly highway, zero mods, never to the track. Within 6 days or so the oil pressure went down then up every time I started. The filter was getting clogged, I didn't know this at the time. When checking the dipstick there were flakes of crap all over the stick, thus floating in the oil. I immediately had it changed. told Goober up to thu' station what was going on and they were so perplexed the gave me a free change. It kept doing it and I changed the filter myself after almost 3 weeks.

At this time was when I started to do a lot of research on oil and on different brands. I also read some info on the Amsoil site and combined with every thing else I read and and was told by different people I switched to Amsoil and before draining the RP I added some engine flush and flushed it well. The problem didn't return after that. Several years later when changing heads and cam, I saw what was left of the film on the surfaces of the engine and in the heads. Now I know that the flakey stuff that was on the dip stick was getting cleaned off by the RP and clogging the filter. It was finally completely cleaned when I flushed it really well. I have other stories from other unrelated people that tell me A) I'll never use Syntec again and B) Royal Purple solves too much, too fast if you've been using an oil that leaves a lot of residue.

Castrol Syntec is NOT a true synthetic oil regardless of the judges opinion.