will it be a good idea to use synthetic oil (pennzoil platinum) in a original 1980 corvette engine or i must stay with regular 5w30 oil ? as i think it will cause leaks...

 

No Penzoil Platinum! See the oil thread at the top of the C3 tech and performance page. You need a high zinc oil. Amsoil, Redline, royal purple and Mobil 1 are synthetics and SOME grades of these do have enough zinc. Others don't so read the thread.

 

http://forums.corvetteforum.com/c3-t...ppet-oils.html

 

I agree with the comments on Zinc, however, if this motor has some miles and is not a recentr rebuild, yes most likely you can cause any small leak to be worse, however if it does not leak now, most likely syn won't create any unless it was about to leak already, personally I change mine religiously every 3K and don't see a benefit.

 

I changed to Mobil 1. I love the stuff. My '01 Kawasaki revs with reckless abandon when I went with Mobil 1 bike oil

All of my newer cars use Syn oil; Mobil 1 in the Honda. Selena (Agip) in the Alfa so I figured I might was well update and take care of the old girl .. in this case my old LS 5 vette.

I did an oil change and promptly went offshore; I work on an oil rig. Two weeks later when I returned I had a nice outline of the oil pan on the garage floor. I ended up pulling the oil pan and timing chain cover and replacing all of the seals!! While I was at it I replaced the timing chain. Oh and I now use Shell Rotella!! There you go! I would not do it.

carbster

 

keep in mind that its not the oil perse that is causing the leaks but rather bad seals plugged with sludge that the detergents in the oil are cleaning out. two camps out there. some say that synth will cause leaks just because it is synth. the other camp say BS.

id like to see actual scientific evidence that synth oil will eat seals.

 

It is not the synthetic oil eating seals. It is the additive package in the oil. Detergents will clean out the sludge caked in the old gaskets sometimes causing leaks. Esters will cause swelling of the seals and gaskets. Some synthetics have no or very little esters. The modern seals and gaskets are way different most that are exposed to oil are hard plastic with silicon rubber sealing surfaces. No cork, no paper anymore so the newer engines don't need esters as much. I like Amsoil AMO 10W-40. plenty of esters and seal conditioners. I have seen none of the issues with gaskets leaking, it is the right weight, it has 1378 ppm zinc and astm testing has shown it is superior to almost everything else out there in a variety of tests.
It is $8.50 a quart. This is the downside.

 

Previously I've seen many comments in CFC3 forum bashing Rotella while claiming Rotella has Hi-detergent and how it's too much detergent.

So how can it be that Mobil's detergent caused carbs LS5 leaks while his subsequent change to Hi-detergent Rotella has not (apparently) caused leaks in his other seals/gaskets? Overall, something don't square up.

Maybe one of those "bad" irregular length polymer chains found in that bad hodgepodge of chain lengths that comprise all non-syn motor oils ... maybe that particular size chain was the perfect size to plug carbster's other potential leaks. kinda like a rudimetary antigen-antibody lock & key model?

Shazam! maybe there's good reason to use various chain lengths. No scientific data or proof. Jeez? who knows?

Regardless, I'm staying w/ conventional truck oil too.

 

FYI, not all AMSOIL products have high levels of ZDDP as many of them comply with the API SM specifications for 30 grade oils. For those looking for high ZDDP oils (noting that none of these meet GM Standard 4178M), AMSOIL makes these oils which all have phosphorus on the order of 1265 ppm, and zinc on the order of 1378 ppm.
AMSOIL SAE Synthetic High Performance 20w50
AMSOIL SAE Synthetic High Performance 10w40
AMSOIL Series 3000 Synthetic 5w30 Heavy Duty Diesel Oil
(Note that this is a CI-4+ diesel oil)

If anyone is looking to pick up any of these, please drop me a PM so I can ensure you get the best pricing possible.

 

I did note that some grades have the ZDDP needed and some don't. Glad to see a supporting vendor / Amsoil dealer on the forum.

 

He pulled the timing cover and oil pan and changed the all the gaskets and seals, then changed to Rotella.
So I don't think changing to Rotella magically stopped an oil leak that Mobil 1 caused, Good possibility his 40 year old gaskets were shot and replacing them stopped the leak.

I am not a fan of Mobil 1.

Bet the levels of esters are low or completely missing. This is what don't square up. This will cause leakage problems.

I also was a die hard Rotella user when it was CH-4, CG-4 and CI-4 rated and I ran flat tappet cams. It was all I used for 30 years.
The CI-4 Rotella tested out at around 1400 PPM zinc.
The CG-4 Rotella tested out around 1600 PPM zinc and was really good stuff.
The problem is that this is reformulated. It still says Shell Rotella T 15W-40 on the container and looks the same. But the CJ-4 rating limits Zinc to under 1200 PPM. Those that used it for 30+ years as I did are sold on it. It was just reformulated a couple years ago so on a car that gets limited mileage the problems of running he reduced zinc and high detergent have not shown up yet on most of these. When it does show up it is too late!

High detergent levels reduce the effectivness of zinc. Fact
Diesel oils are high in detergent. Fact
CJ-4 rated diesel oil is limited to a maximum of 1200 PPM zinc. Most test well under that. Fact
1200 PPM zinc is the minimum recommended for a stock flat tappet engine. Solid flat tappet, faster modern ramp rates and/or heavier spring pressures would require substantially more than 1200 PPM zinc to provide adequate protection. Fact

This would indicate that the CJ-4 rating adopted in 2007 for diesel oil does not provide adequate zinc or protection for even a stock flat tappet gasoline engine.

CI-4, CH-4 CG-4 would have high enough levels of zinc but is still high detergent.

 

Supporting your guesses about what Shell Rotella T (CJ-4) actually has in it, I ran the CJ-4 Rotella T in my GMC 3500HD when I had to do an oil change on the road and had it tested when I drained it out - 842 ppm phosphorus, 1019 ppm zinc.

 

As has been stated numerous times before, modern diesel oils, including Shell Rotella T, DO NOT have the correct amount of ZDDP for flat tappet cammed engines. Why anyone would use a diesel oil in their C3 is beyond me when there are many conventional and synthetic gas oils that have the correct amount of Phosphorous and Zinc. I think old habits are hard to kill!

 

yeah, im going to stick with my original statement.

with the shot gaskets replaces he could have the same mobil and not had a leak. id like to have seen the inside of the oil filter after the oil change to see how much sludge was inside of it.

 

if only there was a thead on here that listed all of the available oils and their Z and P contents.

 

Why? Because over last 2 years or so, lotsa regional guys have successfully run Rotella 15W-40 CJ-4 (and continue to) in their circle track race motors w/ flat tappets, steep ramps & strong springs. Because we know that diesel truck oil works for us.

 

I would bet that just about any oil would work in those circle track engines and even a street engine over the short term. The problem comes using an oil over time. Detrimental effects from an oil with insufficient anti wear additives are not going to show up quickly but will over a period of time. For example, in 2007, the EPA mandated the reduction in ZDDP levels in all mass market oils, key word, mass market oils, not specific racing/high performance oils. In 2008, I was still using a 10W-30 synthetic that had the reduced ZDDP levels, since I did not realize the reduction had occurred. Did my engine blow up, wipe a cam, vaporize from the 1 year of that oil's use? No! Would I continue to willingly use that wrong oil for a flat tappet cammed engine, knowing that there were better alternatives? No! I would be a fool to do that or really like to gamble. That oil worked before the EPA change so using your logic, why should I change, "it works". As another example, I again would bet that I could use the cheapest generic brand oil in my lawn tractor and the engine would run just fine. Would I see the detrimental effects of using such an oil in 1 year or even 5 years, nope, but I would waiger (for you gamblers out there) that you may see some ill effects at 10 years using such an oil.

The bottom line is that the continued promotion of diesel oils for flat tappet cammed engines with insufficient ZDDP in the new world of oils seems to me poor advice, especially when there are many alternatives in gas engine oils, specifically for our engines. Now if there were no alternatives, diesel oils would look mighty good but fortunately that is not the case, presently.

Diesel oils, I am sure are great for, guess what?-diesel engines.

One more item from Mobil 1's, 15W-50 only, website, as another example, for the doubting Thomas's out there. As long as there are facts, use whatever oil you choose, if you don't like gambling:

Mobil 1 15W-50 1200 1300
Boosted, higher viscosity, fully
synthetic formula designed for
performance vehicles.
HT/HS applications.
Racing and Flat tappet
applications. SM None

From the 5 Qt Container Mobil 1 15W-50, to illustrate my point:

"Used by Penske Racing and Vodofone McLaren Mercedes (F1) motorsports teams"
"Chosen by over half of all NASCAR teams for performance in severe racing conditions"
"Exclusively used by Corvette Racing"
"Also used by grassroots racers as well as professionals in a wide variety of race series including ALMS, NASCAR, and Grand Prix racing"

"Mobil 1 15W-50 is a race proven product and is suitable for a wide range of motorsport applications including sprint and endurance racing on both circle and road tracks"-except for those that are running Shell Rotella T, LOL.

Just curious if the diesel oils like Shell Rotella T make those claims on their oil containers or website?

 

jb78l82:
for the past 2 years or so, the only Rotella 15W-40 readily available in our region is the newer 15W-40 CJ-4. A topnotch, new, iron core, lift rule CT specialty, flat tappet cam new racer net about $225-$300; cam only. In our region, CT racers find the right cam profile and often keep & run that cam for several years; some even get handed off/sold off & run in other motors; the cams are Not failing/wearing out. The cams usually have an effective life much longer than 1 season; typically many. You do not have a handle on how it works for US in our region; your logic does not apply to the apps I refer to. I do and mine does. At this point, I also believe I'm being rather kind/subdued here.

-add-
does the Mobil1 15W-50 at your local wal-mart have a label on front that includes wal-mart logo & a blurb w/ wal-mart printed too? Mobil1 in jugs here does. And so did the 15W-50 that WAS sold here? Can you speculate on any significance an oil specially packaged for a retailer might have?

 

Jackson,

Thanx for the kindness! Just my opinion, based on my experiences with my cars and engines. Obviously, you and others do what you want. Just a counterpoint! Nothing personal!

According to Mobil, the walmart version is EXACTLY the same as anywhere else-No difference! I prefer Mobil 1 15W-50, but as stated many times, any oil with the right specifications would be suitable for a flat tappet cammed engine, not just Mobil 1.

One more item on Diesel oils if you plan to use them after all this "fun" discussion-"if you plan to buy an API CJ-4 ready product, make
sure it is licensed against the API CI-4 PLUS specification to ensure
that your older equipment is protected"

 

Depending on what you want to achieve... CJ-4 has a 1200 ppm phoshorus limit. CI-4+ has 1400 ppm. Thus a CJ-4 oil with phosphorus at 1199 ppm phosphorus will meet both CJ-4 and CI-4+ specifications. Not exactly what I'd want for my older equipment. There are still oils on the market that meet CI-4+ but not CJ-4 allowing them to carry more that 1200 ppm phosphorus.