HT4100 Recommended Oil Viscosity

SlxAlxx · #1 (**permalink**) 12-11-07, 04:24 PM

I've seen several different debates on what brand and grade of oil to use in this fine piece of machinery. My service adviser with almost 30 years of experience with Cadillac and a plethora of knowledge of the 4100, has told me specifically to only use 10W30, as per GM's instructions, and not use any stabilizers or additives. I'm in South Florida where the average temperature year round is in the 80s. I'm thinking that is why he told me not to go to a higher grade oil. What do you guys think?

ehall · #2 (**permalink**) 12-11-07, 05:03 PM

You only need a stabilizer if you have some other problem that you have not yet beaten. In my case I have a problem with oil burning off, and low compression in a couple of cylinders. They are probably related to each other and I'm still trying to figure out what the actual root cause is (weak rings? gunk in the cylinders? loose manifold?). Lucas keeps the oil from burning off and gives me some extra compression, but it would be way better to fix the actual underlying problem(s) (and yeah I'm trying to find it). If you don't have those problems you should stick with the native stuff.

Having said that I will probably switch to Castrol synthetic once I have my engine fully cleaned and operating efficiently.

caddeville · #3 (**permalink**) 12-11-07, 05:15 PM

10w30 in a 4100? hahahahahahahahahahahah, i did that, lets see, my lifters would get stuck, my bearings would knock, and the car would sluggish and my gas mileage sucked. Now when i put AMSoil 15w40 full synthetic, i don't seem to have any problems and i run a little bit of lucas also. My 4100 goes pretty damn good and doesn't have any huge issues.
AMSoil 15w40 full synthetic and Lucas is what i run in my engine.

zz_camaro_zz · #4 (**permalink**) 12-11-07, 07:59 PM

Quote:

Originally Posted by caddeville

10w30 in a 4100? hahahahahahahahahahahah, i did that, lets see, my lifters would get stuck, my bearings would knock, and the car would sluggish and my gas mileage sucked. Now when i put AMSoil 15w40 full synthetic, i don't seem to have any problems and i run a little bit of lucas also. My 4100 goes pretty damn good and doesn't have any huge issues.
AMSoil 15w40 full synthetic and Lucas is what i run in my engine.

do you still use that in the winter or do you down grade a weight or two?

caddeville · #5 (**permalink**) 12-12-07, 02:18 AM

nope the AMSoil 15w40 isn't thick like the regular rotella 15w40, its goes down liek normal oil, my caddy is garaged so its warm enough, i switched to full synthetic 10w30 once in january to see if ym lifter problem would go away, HELL NO it didn't, i ran SEAFOAM thoruhg it, and damn my engine sounded liek shit with 10w30, and didn't have the same off the line power as when i run 15w40 full synthetic

ehall · #6 (**permalink**) 12-12-07, 02:41 AM

Actually I was probably too strong in my earlier post. I would say that anybody who has a 20 year old engine would benefit from a little bit of Lucas, in that it will return some compression and offset some power loss. I would start with half a bottle (they are 1 liter I think), and would not use more than that unless you are having some other problem (loss of oil, excess noise, whatever). I put a whole bottle in my HT4100 and it made all the difference in the world, but I put the same amount in my 91 Jeep Cherokee with 334k miles on it and while it did stop a rear main seal leak it also dropped my power a bit by making the engine have to work harder.

ht4100 · #7 (**permalink**) 12-12-07, 09:56 PM

I just changed the oil in my 86 Seville with 10w-30 regular castrol. I haven't noticed any noises or anything, runs smooth, I ran the same stuff in my 83 seville, ran smooth also. I live in nebraska, hot summers, cold winters. Most people run 15w-40 in 4100's?

SlxAlxx · #8 (**permalink**) 12-12-07, 10:43 PM

Quote:

Originally Posted by ht4100

I just changed the oil in my 86 Seville with 10w-30 regular castrol. I haven't noticed any noises or anything, runs smooth, I ran the same stuff in my 83 seville, ran smooth also. I live in nebraska, hot summers, cold winters. Most people run 15w-40 in 4100's?

Thank you! I knew I wasn't crazy.

awadecki · #9 (**permalink**) 12-13-07, 01:35 AM

OK, I currently own three 4.x engine cars, and here's my recommendation:

When the temperature outside is above 32 degrees Fahrenheit, I use regular Rotella 15w40. Rotella is a great oil, with lots of lubricating properties for diesel and gas engines. It used to contain a lot of ZDP, or a zinc additive, but has since been reformulated. Many people don't know this, but today's oils actually have LESS anti-wear additives than they have in the past 30 years! The best anti-wear additive, zinc, was excluded from many oils because it created excess emissions and lowered fuel economy. However, HT4100 engines need an oil with great lubrication--and something like zinc--primarily because they have non-roller lifters, and their camshafts are somewhat soft (GM's Saginaw Division eventually admitted to supplying GM with soft-core camshafts). All 4.5 and 4.9L engines have roller lifters, and the cams were much harder.

In the winter time, I don't really drive my car (trying to save it from the plethora of salt Michigan likes to throw on its roads), but I would run a regular 10w30 with one change: buy a bottle of camshaft prelube from your GM dealer, and add about 1/3 of the a bottle to the oil. This little bottle is like lubrication magic: it contains TONS of zinc additive, which protects the lifters and the entire engine. I've considered using synthetic Rotella 5w-50, but, as I said, I don't drive the car much in winter.

Do NOT use any other additives (e.g. Lucas) in your oil. They're not made to be in there. I used to add a bit of GM Engine Oil Supplement in the oil, but GM has since discontinued it. Why? Because it contained too much zinc for those EPA folks.

In short, for any car that you have with non-roller lifters, I'd use either Rotella, or a 10W-30 with some camshaft prelube, or both. I also own an 82 Trans Am and an 86 Cutlass Ciera, and I use regular oil (10W-30 for the T/A and 5W-30 for the Cutlass) plus about 1/3 of a bottle of GM's camshaft lifter prelube in both cars. The T/A doesn't have roller lifters, so this camshaft prelube helps; the "Gutlass Cutlass" has the Iron Duke 4-banger that has roller lifters, but it has a nylon camshaft gear (no timing chain) that notoriously went bad around 100,000 miles. (By the way, GM's 3.8L engines are also have nylon timing gears that fail around 100,000 miles if not changed--if you have a 3800, a plastic cam button on the inside of the timing cover will also break at around this point, so change it as preventative maintenance!)

One other thing: if you have a 4.x engine car, and it's cold where you live (under 45 degrees), let your car idle for about 30 seconds to a minute before you drive away in the morning. If it's colder (say 10-15 degrees), let it idle for a bit longer. Then, when you drive off, drive gingerly until the heater has been on for at least a few minutes--this means you've pretty much reached operating temperature. This is more true for those of us with HT4100s, than those of you with 4.5s and 4.9s.

Letting the car idle and warm a bit will allow the aluminum block and iron heads to expand more slowly, reducing the risk for a head gasket failure. I surmise that one of the reasons why the 82-85 RWD Cadillacs equipped with the HT4100 burned them up so quickly was because their owners would start them in the winter, and then have to floor the car to get it up to speed. This put a lot of stress on the head bolts, and made the metals expand much faster than letting the car idle for a bit before driving off.

caddeville · #10 (**permalink**) 12-13-07, 02:26 AM

i use AMSoil 15w40 full synthetic with a little bit of Lucas, my car is always garaged. So whats the best for the 4100?

awadecki · #11 (**permalink**) 12-13-07, 02:51 AM

Preferably anything with lots of anti-wear additives (i.e. not just regular oil), unless you add something like GM camshaft prelube to it.

ehall · #12 (**permalink**) 12-13-07, 03:31 AM

this post suggests that modern oil has plenty of ZDP for the job required

awadecki · #13 (**permalink**) 12-13-07, 12:18 PM

Very nice post.

I agree with a lot of what has been said, but it is true that today's oils have less ZDP than they did in the 1970s and 1980s. There's no question that HT4100s have soft camshaft cores (and also soft distributor gears), along with flat tappet lifters. In my mind, I want more ZDP in my oil than what oil makers currently put in there. That's why I only use 1/3 of the bottle of camshaft prelube instead of the entire thing: it's just a little extra boost to help prevent scuffing.

Additionally, remember that most HT4100s are running around with some of their cam hardening wore off from coolant mixing in the oil. Many owners took a while before they realized an intake/head gasket was leaking, and in the process, damaged/destroyed their engines crankshafts and camshafts. I recently had a new cam put in my 85 Deville, and with only 37,000 miles on it, it had 4--yes, 4--flat lobes (I mean totally flat), and about 6 more that were visibly rounded off. The crankshaft had already been replaced before I bought the car.

ehall · #14 (**permalink**) 12-13-07, 01:03 PM

how much did it cost you to get the new camshaft installed

awadecki · #15 (**permalink**) 12-13-07, 03:55 PM

$270 in parts and $600 in labor...I got a deal. It was installed by a mechanic at a Cadillac dealer who does work on the side at his house. He did an excellent job. Even fixed things I didn't ask him to (like my broken spark plug wire conduits) for free! He's in SE Michigan.