Okay, I know that the topic of 'Best oil' has been discussed and beaten to death, and I know all about 'Bobs the oil guy". However I just wanted to see if everyone would post what has been working out for them. I just got my wife's '06' MalibuMaxx back from the dealer and it had a 'Front Crank Seal Leak' at only 23,000 original miles. Luckily under warranty. It has gotten the Goodwrench treatment at every OLM on the dot. My Blazer had its Crank Seal replaced after a leak was discovered at only 27,000 original miles and has gotten Premium Synthetics since its first oil change every 3k miles (has no OLM). I am concerned as my Blazer warranty has 30 days left and the Malibu has 1 yr. Both vehicles get the recommended 5W30. Should I use a little thicker oil? 5w40? I hate leaky cars, especially when they get taken care of vigorously. What's your take guys?

 

If you have studied on "BITOG", then you've already gotten the info from the best. Our engines are not picky about their oil. Running any name brand (and in your case, synthetic) in 5W30 or 10W30 should be just fine. I would not recommend any *W40 oil unless you have a leak going on and need a temporary solution.

 

My favorite combo is Castrol for my Blazer,Bmw,4Runner is CASTROL FULL SYNTHETIC, and a qt ofFULL SYNTHETICLUCAS, the oil pressure is great, no leaks, no oil burning.

 

The only difference between passenger car motor oils is the viscosity since the factory hydraulic roller cams were introduced. The EPA has required oil companies to reduce the zinc (ZDDP) content to .14 PPM in passenger car oil. Long haul truck oil such as Shell Rotella and Valvoline Racing oil has the highest zinc content but no more than .14 PPM. A hydraulic flat tappet cam will go flat in a few thousand miles usinglow zinc oil. In 1973, the EPA made GMeliminate the oil spit hole on the cam side of the rod in order to reduce oil spray on the camshaft and cylinder walls. This was another effort toreduce emissions.GM tried to make hydaulic flat tappet cams work with lowvolume and low zinc oil in the mid-1970s but had too many warranty claims for flat cams. In 1972, the automakersreduced the valve spring pressure on the "high performance" engines with little result. They finally tooled up and introduced roller cams so the engines can use low zincmotor oil and normalvalve spring pressure. Roller cam toolingadded about 8% to the cost of eachvehicle that was naturally passed on to the customers.

The U.S. Congress should GIVE (not loan) 10 billiondollars to the U.S. automakers because the U.S. Government agencies such as the EPA and NTSBare mainlyto blame for the automakers going broke.

 

I guess I was asking if using a thicker weight oil would prevent these GM seals from leaking. I have seen people use the Rotella 15w40 in the 4.3s. I would never go that extreme, but I am currently using 5W30 Fully Synthetic all year round in the Blazer, and 5W30 Goodwrench all year round in the 3.5L Malibu. I am not hard on either vehicle and would like to see them last me another 5 years without major problems. i plan to keep the Blazer for life to tow and go camping with.

thanks

 

I would say that you were lucky enough to get two vehicles with leaky seals. This is not a common occurrence for the 4.3L that "young". I can say that synthetic oil is not helping the situation. In my experience with a leak on my 2k Bravada, synthetic leaked out a LOT quicker than regular dino oil. My leak looked to be a rear main seal leak, but upon further inspection, it ended up being loose pan bolts. Tightened them up and the leak was gone. Then I made the switch back to full synthetic.

While heavier oil may stop it from leaking out, it can cause lower fuel mileage amongst other things.

 

Never use a heavy viscosity oil as a stop leak. It don't work. I don't trust10W-40/50 multi-viscosity oil and only use 10W-30 even in a high milage engine. Heavier weight oil is more difficult to get moving in a cold engine on start-up even if it is suppose to be 10w when cold...I dont believe it.Most of engine bearingwear occurswhen you start a cold engine. Pour some 10W-40 or 50 and pour 10W-30 in comparsion and you can see the 10W-40 flows slower.Heavy viscosity oil is for high pressure engines such as engines with more than11:1 compression ratio, nitrous oxide, turbocharged or supercharged. Those type high performance and racing engines over-pressurethe rod and main bearings during the power stroke and require harder bearing material and higher viscosity oil.

I should know about rear main seal leaksbecause dealers and owners of Pontiac V8 engines have beengrappling withthat problem for 53 years.The one pieceChevy rear main seal solved the problem of a rear main seal leak butproduction of Pontiac V8 engines ceased in1979, before GM introduced the one piece seal.

It is very rare that a Chevy V8/V6 with a one piece rear main seal would leak. The next time you are under the car, tighten the bolts at thetwo pan rail reinforcements and make sureall the pan bolts are in placeand snug them up, especaillythe rear pan bolts.Chevy introduced the pan rail reinforcements so you can tighten the bolts holding them more than the rest of the pan bolts. Pan gasketsis the major source ofoil leaks on Chevy V8/V6 engines withthe one piece seal.

Check and see if yourpan rail reinforcements are missing. Someimes the workers in the assembly line engine shopfailed to put them on. Theleak usually did not occure untilthe vehicle was well out of warranty.If your pan rail reinforements are missing you can still order new ones for $7.63 ea. MSRP. The pan reinforcementsmay have been for a factory recall since they did not use them on any engine except the 4.3L V6.

1988-1995 4.3L engine
GM-10172766, oil pan reinforcement, RH
GM-10172765, oil pan reinforcement, LH
.

 

Duntov,

Great info, are you a technician? I sort of understand what you are talking about with the reinforcements, but what do they look like? Do you happen to have torque specs on the bolts?

Any advice on the Malibu 3.5L? From what I have been reading, crank and intake manifold seals are a common demon for these engines. Maybe thats whey they only had a 4-5yr lifespan before the 3.6 took its place.

 

Your truck does not have reinforcements as the oil pan is aluminum.

 

The Chevrolet parts catalog lists the pan reinforcements for all 1988-1995 4.3L engines and does not differentiate betweena aluminum or steel oil pan.

Use Permatex Super High Tack 97B (1.75 oz. tube) gasket sealant for anything on an engine or anything else includingthewater pump and transmission pan. I onlyapply it to the accessory side of the gasket. Position the gasketon the acessory and let it set it set for 10 minutes before installing the part on the engine. Wipe off any excess on your fingers or engine with lacquer thinner. Even though the instructions say to apply the sealanton both sides of the gasket, I neverapply sealanton the engine side of the gasket, just make sure that side is clean and dry.I never usethe popular anerobicsealants on anything because any excessmay squeeze out andfind it's way into theoiling or cooling system of the engine and can restrictradiator flow or clog up the oil pump pick up screen.

I believe the maximaum torque is 15 lb. on the pan bolts and 20 lb. on the reinforcementbolts.