I'm going full synthetic in my 1994 5.8, now that my motor has 100,000 miles on it, anyone think this is a good idea? I picked up mobil 1 10w30 its full synthetic and good for high mileage motors it says.I just changed the oil 2 weeks ago, but after the dealer did a fuel injection flush I checked the oil and it was quite dark, so thought I would change it again, and do the synthetic thing, what kind of mileage are you synthetic users going before changing the oil? I noticed the red line synthetic oil was like 12.99 per quart apposed to 7.99 for the mobil 1 is it really that much better? I'm use to paying like 3.00 per liter for regular oil, so 7.99 for mobil was a jump just couldn't bring myself to pay 12.99 for red line

 

If you put synthetic in a high mileage vechicle that has never had it before get ready for some oil leaks cause its gonna pour out everywhere

 

talk to me man! talk! yikes what do you mean? WHY???? fill me in before I do this, how can that be possible? you mean it leaks threw all the gaskets?? never heard of that

 

Not true, synthetic oil does not cause oil leaks. The only difference between syn and dyno is synthetic was created with a catylist in a chemical plant, where dyno is refined crude. Most are mixes anyway. I have put full synthetic in 3 vehicles without using it before with no problems. It may leak if you buy a synthetic with high detergents like mobil 1, but its not the oils fault. Its your gaskets.

 

changed my old trucks oil to full syn and my brothers, both them started leaking oil before 3000 miles. dunno why but they did rear seal on my truck started pouring.
i dont understand why this happen but would like to. my friends 88 ford f150 had 179,000 on it. he went full syn and never had a problem

 

Getting leaks after switching to synthetic is due to having bad gaskets in the first place. The synthetic oil cleans out all the crude left behind from the normal oil. It doesn’t really matter, if the gasket is bad you were going to have to change it sooner or later anyway.

 

well thats true if it was bad in the first place it would need replacing anyway , but it is alot of work just to run synthetic

 

My dad has a '90 F-250XLT Lariat with the extended cab, 351 (He says it's a cleveland, but I'm pretty sure it's a windsor now) and the automatic. was a package deal ford came out with here in canada. Anyhoo, he ran full synthetic from oilchange 2 (came with conventional oil, he changed it with conventional, and then asked the dealer if full syn woud void the warranty). and did the oil changes religiously every 5000Km (3000 miles, give or take). used Mobil1 10W30 every time. At 160K Km, his engine had so much crap and sludge, and carbon deposits in the lubrication system that there were 1/64 inch groves scored into the crankshaft around the main seals. His oil pump was failing, and the engine was struggling all the time. there was no problem with the fuel system, or the ignition system, was all the lubrication. his engine started puking oil, and he had to get it replaced.

every mechanic I trust says synthetic isn't worth the cost. sure it doesn't break down as fast, but when it does, watch out. and it costs 4 times as much as regular cheap conventional.

just my $0.04 CAD, taking into account the exchange, and inflation

Dave

 

wow!! you guys got me thinking, I don't want a heep of problems by changing to synthetic, and mobil 1 was what I picked up. I'm going to hold off a bit here before I do this, here I thought I was going the whole 9 yards and splurging on the big buck oil, any other ideas for a high mileage motor? any conventional oils thats formulated for this purpose, maybe a guy should just use regular oil and change it more often

 

Unless the vehicle is turbocharged, I use ordinary liquid dinosaur, and as the engine wears and has more clearances in the bearings, I simply use a slightly thicker oil so the increased bearing gaps can be filled with oil properly.

For turbocharged vehicles, I always use synthetic only because the breakdown temperature of synthetic is higher than "regular" oil, and turbo bearings of course are significantly hotter than any bearing in your engine, because of the heat conduction from the exhaust. This helps reduce bearing coke, which is probably the nastiest stuff to scrape off a bearing

My truck has 284K, and still gets oil changes every 3000 miles using boring, ordinary oil. I just haven't used 5W30 for about 150K or so.

 

Frederic,I've been using 10w30, should I go to something alittle thicker? what would you recommend,I got 100.000 miles on the truck. I think I'm going to take the synthetic oil back, and use dinosaur( I wonder if those critters knew they were going to end up in our crankcases) thanks Randy

 

I used synthetic oil from 6,000 miles and took my engine apart at 230,000 miles and all the parts, from the bores, to the pistons, to the crank, cam lobes, everything, mic'ed out at brand new specification. Also the inside of the engine was as clean as if it had been freshly assembled the day before. That was with 4,000 mile intervals. I pulled the engine because of leaks. The gaskets were ok, but I worked for the DOT and parked on salt all the time. This rotted the pan ,and the side cover to the point that they were perforated. But the synthetic kept the engine like new. And that was with alot of heavy hauling and hard use. 230,000 miles with less than .001" of cylinder wall taper and still having crosshatch on the walls is pretty impressive, especially with the lack of varnish and sludge. My truck is a 96 F-150 with a 4.9l six. My 1984 Olds 98, however, got converted at 132,000 miles. When I converted it, I had to change the oil 4 times in 1,000 miles because it dissolved all the sludge and varnish and crud inside the engine. It also started leaking, because the sludge and varnish and crud plugged up all the leaks. It needed a set of valve cover gaskets and a timing chain anyway, so it didn't matter to me. When I took the valve covers and the timing cover off, though, the evidence told the story. All the varnish and sludge were gone. The synthetic litterally flushed my engine clean.
I totaly believe in synthetic, but at the same time, would caution you against putting it in a high milage engine unless you planned on doung gaskets anyway. BTW, when used from new, synthetic helps keep gaskets and seals conditioned. Also, it increases gas milage due to reduced friction. My buddy just changed over his Crown Vic and got 2 MPG. That's 2 MPG of friction eliminated. That is impressive.

 

Let me rephrase that NOT GOING FULL SYNTHETIC, I'm not taking the chance of a bunch of oil leaks, so I took the oil back, and picked up valvaline 10w30. whats up with theses fram double guard oil filters, I was looking at them at the local parts store today, there like 12.00 over a ordinary house brand 5.00 filter, which the parts guy says is made by fram, I looked them over close I couldn't see a difference in out side design, anyone use the double guard.I know theses are elementry questions, but what the 773H

 

Why not go 20W50 Valvoline or other brand if its always reasonably warm where you are. I've always thought that multi viscosity is a crock of ****. I can't see how an oil can be one way at startup then suddenly change. Its either a thin oil or a thick oil in my mind, not both. I think 5w30 and 10w30 are too light for a V8 truck engine especially if its used as a truck.

 

I run 10W40 in my truck and am starting to have oil pressure problems. Thinking about going to 20W50. My grandpa taught auto mechanics for 25 years. He always swore by Castrol GTX. I have been told though that valvoline actucally holds a better pressure than most. Any Comments....