Yes i've heard that before. I would think: also under normal driving conditions and a factory original non rebuild engine (old gaskets) ? I run 15w40 and getting a full synthetic here in a parts shop is mostly a lot lower oil viscosity or a lot higher like 10w60 or 20w50. There is semi synthetic here in the correct weight but i don't think semi synthetic is worth it. Listening to the Amsoil guy in Vegas i should go for 10w30 Classic Oil by Amsoil. With a 1000-1200 miles a year i'll stick with a quart of Valvoline 15w40
Using 5W30 for pumpability and to keep pressure related power loss and front cam bearing and distributor roll pin wear and stress minimized.
Yeah if you want to burn even more oil.....motors back then were not designed for 5 weight oil! Maybe if temp no higher than 32deg.......
I asked Amsoil about Synthetic oil for my 1970 Buick 455. Amsoil is the original Synthetic creator. Hope all find this information useful. VET (Navy) Foy White to Amsoil: Sent 15, May 2023 I have a 1970 Buick GS 455. I want to know if I can run your Synthetic oil in my car. Because I have a flat tappet cam, I either need an oil with Zink in it or I have to add Zink additive into my oil. What line of Synthetic oil do you recommend I use. My engine has been rebuilt about 3,500 miles ago. I've been told my mechanics that I can't use Synthetic oil because it's to light and my bearing clearances are too large for this thin oil. That doesn't make since to me at all, I would think a thinner oil would give more oil volume to the bearing plus bring more cooling to the engine. Maybe I'm wrong, but I don't think so. Please give me Professional advice on using your product. Please displace the myth on using Synthetic oils. Regards, Foy J White Jr I live in zip code 22153 Product Recommendations: Finding the correct products for my application. Amsoil response: Foy, Thank you for your email. The AMSOIL ZROD synthetic engine oils are recommended for this engine. The ZROD oils are formulated with high levels of zinc antiwear chemistry, plus additonal rust and corrosion inhibitors for classic vehicles for added protection. Synthetic engine oils are not any thinner than conventional oils, so the mechanic may be mistaken about this fact. The ZROD is available in SAE 10W-30, SAE 10W-40, and SAE 20W-50 viscosity grades to be suitable for any type of engine build. We hope this is helpful.
I think it's interesting that Buick rebuild instructions generally specify tighter bearing clearances than on similar displacement, or similar crank-journal-size engines from other manufacturers. And then we're hearing that they need thicker oil. Doesn't make sense. Tight bearings need thinner oil. Everything else--rings, valve stem clearance, oil drainback, hydraulic lifter operation--is either identical, approximately the same/similar/"close enough" to those other engines. And bearing lube/cooling would be paramount.
I think the original rope seals are one good reason to think about lighter weights and slipperier materials(synthetics) carefully. I agree though that seems like nonsense (needing a heavier weight) especially if it’s a rebuilt with tight tolerances and modern seals. I went to 5-30 Mobil 1 in my Stockish rebuilt 350 this summer and that seems just fine. Hot pressure a tick above 10 at idle in drive… Only leak is tiny drip at corner of the oil pump housing that amounts to nothing other than bugging me.
New motors these days have way tighter clearances than old Buick motors. Some run 0W-20. If you can get 70+psi hot with 5w-30 at 6000 rpm go for it. I need 10w-30 for that and to have 20+ at hot idle. I'd rather have a bit more pressure than less. Extra protection IMO....especially in this kind of heat we are seeing.
I like tighter tolerances as long as they are consistent and not wildly high and low, aka .0015 on one bearing and .0025 on the other. I've got all modern seals in my engines. I've been running synthetic 5W30 in my 462 I built several years ago with no issues. It holds 15-20 at hot idle and hits 60-70 at hot over 2500 RPM. Only leaks have been around the valve covers and I've replaced them with the T/A reusable ones. My recently rebuilt 350 is holding excellent pressure on the factory gauge when hot after I took the Stage 1 spring out but I'm running straight SAE30 break-in oil still. Hard to get many miles on a car with all this rain we've been having. I'll put four quarts of 5W30 in it at first oil change and see where it stands. I can always add a quart of 20W50 to get it up to 8W34 and put the Stage 1 spring back in if it still doesn't suit me.
The 400-430-455 engines use a crank with big 3.25" mains. The bearing speeds are higher. Buick used tighter clearances to minimize pressure loss from the front of the engine, where the oil pump is, to the rear. I am sure everyone is familiar with Buick High Performance recommendations,
Pontiac 421, 428, and 455 also use 3.25" diameter main journals. If you tell a Pontiac guy you're using .002 maximum for main bearing clearance except on the rear main where you'll go as high as .0025, he'll think you're committing engine murder. https://www.speed-talk.com/forum/viewtopic.php?t=5325 The only reason Buick needs such tight clearances is because of the crappy oiling system that has trouble supplying enough pressure/volume to the critical areas especially as the pump and front cam-bearing wear. The tight oil clearances are a crutch. And tight clearances demand thin oil so it can flow and cool the journals/bearings.
Yes, Pontiac uses a pump in the pan. Definitely better, and yes the Buick oil pumps are in the front timing cover. Not optimal but it is what it is. We all know what happens if you build them too loose. Lack of oil pressure at the back of the motor toasts the #7 and 8 rod bearings. Despite that, BBB engines went 100,000 miles plus without problems. It's only when you intend to turn higher RPM that it can become a problem. Denny Manner said, it isn't the power, it's the RPM. Still, there are engines that built correctly can be dependable even with the crappy oiling system. Racing engines are built with looser clearances. My engine is built looser than .002, it has seen 50+ 1/4 mile passes, it has great oil pressure, and it is still together and running great 11 years later. I use 10W/30 oil. The TA grooved cam bearings eliminated the cam bearing problems, and the pump is fine as long as you set it up correctly, and change your oil. The speedtalk link seems like they are discussing racing engines.
There are other V8 engines with the oil pump up front too, are they all less effective then the Pontiac design? Thanks.
It makes for better oiling to have the pump inside the pan. The Buick pump in the timing chain cover is worse, but as long as it is set up correctly, and bearing clearances are appropriate to the intended use, the Buick pump can supply enough oil for everything except all out racing/track use. I really wish Buick would have pointed the oil filter down so it stayed full all the time. My 3800 V-6 was like that.
I have a 90 deg adapter on my 67GS400 fabricated to clear the steering box when it was converted to RHD in Australia in 67 , tis currently buried in the garage , I’ll send some pic when I dig it out . On the oil consumption topic , i would expect an engine of that age and the low annual mileage, to find the oil rings stuck in their grooves , I would do plug reading , pull the pcv valve , poke a screwdriver down to check the tin inlet manifold is intact, maybe run some 15w40 high detergent Diesel oil .
