Royal Purple 10w-30 SL Rated?
04-25-2011, 12:26 AM
#1
Safety Car
Thread Starter
Royal Purple 10w-30 SL Rated?
I read the sticky, and have been doing lots of reading on here and elsewhere...
But it seems that the SL rated oil is borderline ok to use in our flat tappet engines? Is this right or wrong?
I still got the car up in the air and just added the oil...but have no problem with draining it again and putting in an oil that that has more ZDDP additive.
It is also a synthetic oil...which I heard is bad in our older engines, due to it's more solvent nature, and our worn engines..should I be worried? Is it too late to switch back to regular? I haven't started the car back up..
Thanks!
But it seems that the SL rated oil is borderline ok to use in our flat tappet engines? Is this right or wrong?
I still got the car up in the air and just added the oil...but have no problem with draining it again and putting in an oil that that has more ZDDP additive.
It is also a synthetic oil...which I heard is bad in our older engines, due to it's more solvent nature, and our worn engines..should I be worried? Is it too late to switch back to regular? I haven't started the car back up..
Thanks!
04-25-2011, 06:58 AM
#3
Le Mans Master
Synthetic oil is not bad for older engines! The myth that synthetics can cause links is also not true-engines with weak gaskets or with current leaks can get worse with synthetics simply because a synthetic oil has molecules that are all the same size which squeak past a bad or weak gasket where conventional oils have molecules of all different sizes. As long as the synthetic has adequate Zddp you will be fine. Hope that helps!
04-25-2011, 07:25 AM
#4
Drifting
I second that.
I think some of those rumors come from some mechanics. There is one near here, who makes those statments. He runs a service station. Therefore does many oil changes. He's been in town for a long time, and has a good following.
He has gone so far as to tell folks that synthetic is bad for older engines, and it cannot mix with original oil. That once you've gone synthetic, you can't go back.
People believe this guy since he has experience.
I think some of those rumors come from some mechanics. There is one near here, who makes those statments. He runs a service station. Therefore does many oil changes. He's been in town for a long time, and has a good following.
He has gone so far as to tell folks that synthetic is bad for older engines, and it cannot mix with original oil. That once you've gone synthetic, you can't go back.
People believe this guy since he has experience.
04-25-2011, 12:38 PM
#9
Safety Car
Thread Starter
04-25-2011, 02:49 PM
#11
Safety Car
Thread Starter
@ SW: I read many many threads through searching on here..maybe no one reputable said it, but there were a handful who all said the same thing. 
Originally Posted by Birdman @ Royal Purple
Car:
1968 Corvette Convertible
327 (Heads and block are stock)
4 speed manual
I just dumped 3 bottles of your Royal Purple Synthetic 10w-30 into the engine, with a filter change...but realized after that I forgot to check its ZDDP ratings. It seems that nothing is said about that version's ratings, and it has "SL" specifications on the bottles...which means lower ZDDP. Do I need to go get new oil that has known higher levels of ZDDP for my old flat tappet cam, before I start the engine again?
1968 Corvette Convertible
327 (Heads and block are stock)
4 speed manual
I just dumped 3 bottles of your Royal Purple Synthetic 10w-30 into the engine, with a filter change...but realized after that I forgot to check its ZDDP ratings. It seems that nothing is said about that version's ratings, and it has "SL" specifications on the bottles...which means lower ZDDP. Do I need to go get new oil that has known higher levels of ZDDP for my old flat tappet cam, before I start the engine again?
Originally Posted by Royal Purple
Good Morning Mr. Bird,
If the engine is a stock build, the ZDDP level in Royal Purple SAE 10W-30 (part #01130, quart bottle) should be sufficient. If you have a more aggressive camshaft installed and/or you have the L79 engine (350hp, 327), Royal Purple SAE 10W-40 (part #01140, quart bottle) would be a better choice because it contains more anti-wear additive.
If the engine and seals/gaskets are in good shape, there is no issue. However, if the seals and gaskets are marginal and engine deposits are actually sealing the engine, the engine may start showing seepage or minor leaks. Other than that, there are no risks to switching to a high quality synthetic engine oil of which we are aware.
Thanks for choosing Royal Purple and have a great day!
If the engine is a stock build, the ZDDP level in Royal Purple SAE 10W-30 (part #01130, quart bottle) should be sufficient. If you have a more aggressive camshaft installed and/or you have the L79 engine (350hp, 327), Royal Purple SAE 10W-40 (part #01140, quart bottle) would be a better choice because it contains more anti-wear additive.
If the engine and seals/gaskets are in good shape, there is no issue. However, if the seals and gaskets are marginal and engine deposits are actually sealing the engine, the engine may start showing seepage or minor leaks. Other than that, there are no risks to switching to a high quality synthetic engine oil of which we are aware.
Thanks for choosing Royal Purple and have a great day!
Originally Posted by Birdman @ Royal Purple
Thanks for the quick reply.
As far as I can tell, it is the 300hp version. However, I've been told by others, that it sounds like it has a slightly more aggressive cam. It may very well be the 350hp L79 (or the previous owner changed cams).
Additionally, I have installed the following:
Weiand Stealth Air Strike Intake Manifold
Barry Grant Road Demon Carb
Switched from stock points to Summit HEI distributor, and larger wires, and bigger gapped spark plugs (.045)
Hooker Side-mount Super Competition Headers and Sidepipes with Spiral Tube Baffles
Polished Aluminum Water Pump
Premium Fuel
With these additions, would you recommend I step up the ZDDP content by switching?
I noticed on the short test drive today, that the engine was running a bit hotter than the other day..is that because I went down to a 10w-30? What's the risk of running 30 instead of 40?
As far as I can tell, it is the 300hp version. However, I've been told by others, that it sounds like it has a slightly more aggressive cam. It may very well be the 350hp L79 (or the previous owner changed cams).
Additionally, I have installed the following:
Weiand Stealth Air Strike Intake Manifold
Barry Grant Road Demon Carb
Switched from stock points to Summit HEI distributor, and larger wires, and bigger gapped spark plugs (.045)
Hooker Side-mount Super Competition Headers and Sidepipes with Spiral Tube Baffles
Polished Aluminum Water Pump
Premium Fuel
With these additions, would you recommend I step up the ZDDP content by switching?
I noticed on the short test drive today, that the engine was running a bit hotter than the other day..is that because I went down to a 10w-30? What's the risk of running 30 instead of 40?
04-26-2011, 03:12 PM
#12
Pro
Member Since: Apr 2006
Location: Southern California
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Keep in mind that, that API Service Spec of 1,000 ppm zinc/phos for SL oil, is the MAX it can have in it. It does NOT mean that, that is how much is actually in it. I sent a sample of 5W30 Royal Purple SL oil to Blackstone Labs maybe 3 years ago. The report I got back listed:
864 ppm zinc
737 ppm phos
So, you may well be getting less zinc/phos than the bare minimum of 1,000 that you are looking for. But with that said, RP's proprietary "Synerlec" anti-wear/extreme pressure additive, is probably still enough to keep you out of trouble. But I don't have any hard data to back that up. Though RC81's trouble free experience would certainly seem to support that assumption.
Oh, and Birdman is absolutely correct. Oil companies frown on ANY additive being mixed in with their oil. They go to a lot of effort to perfect their oil's additive package. This is all complex chemistry developed by chemical engineers. And if/when someone pours in something in addition to theirs, it can mess up that additives overall package, possibly making it worse than it was to begin with. A word to the wise is to only put in your engine what comes out of the bottle. If you don't like a particular oil the way it comes, then select an oil that you do like. There are plenty of oil options out there, for anything you need.
864 ppm zinc
737 ppm phos
So, you may well be getting less zinc/phos than the bare minimum of 1,000 that you are looking for. But with that said, RP's proprietary "Synerlec" anti-wear/extreme pressure additive, is probably still enough to keep you out of trouble. But I don't have any hard data to back that up. Though RC81's trouble free experience would certainly seem to support that assumption.
Oh, and Birdman is absolutely correct. Oil companies frown on ANY additive being mixed in with their oil. They go to a lot of effort to perfect their oil's additive package. This is all complex chemistry developed by chemical engineers. And if/when someone pours in something in addition to theirs, it can mess up that additives overall package, possibly making it worse than it was to begin with. A word to the wise is to only put in your engine what comes out of the bottle. If you don't like a particular oil the way it comes, then select an oil that you do like. There are plenty of oil options out there, for anything you need.
Last edited by 540 RAT; 04-26-2011 at 03:18 PM.
