Running Synthetic after running regular oil

[DJ JEFF]

I am thinking of switching from using regular oil to synthetic. I have heard of some people saying that switching after using regular oil will cause leaks. My Tahoe with a 5.3 in it has 42,000. Does anyone know if this it true? Also it uses about 1qt to 1.5qt every 3500 miles. The stealer says this is perfectly normal. (ya right!) Just like all of the other problems that I have taken to them on this grand SUV. Iss normal man. You lookin good in that Tahoe man.

[sa200]

maybe u should just use regular 10w-30 , lighter oil will just be consumed faster...

[95tahoe4x4]

I dunno, but I think you are leaking a little. I have a 95 with 106,000 and I only leak 1/2 quart every 3,000, running 5w30, like GM wants them to run. It must be leaking just enough to use oil, but not drip on the garage floor. Crawl under it and take a good look around, if you are leaking, get them fixed then switch over if you choose. It will consume some of the syn, it could leak as well, your call. If you are not leaking at all and still consuming, try switching to Castrol, 5w30, my brother was comsuming, switched over to that and stopped, dunno why, but it stopped.

[Danny Demon]

I have a 96 Tahoe that I switched over to Mobil 1 5W30 at about 35,000 miles. The synthetic will clean up your engine so you might want to make your first synthetic oil change interval by 1000 miles. Use a good filter. After that you can go to much longer intervals. I regularly go 5,000 miles between oil changes. Mostly highway mileage. My Tahoe now has 100,000+ miles and it still runs like new. The longest I have ever went between oil changes was 9,000+ miles after a series of runs out West from here in the Midwest during a family crisis situation. Used about half a quart. Tahoe had over 80,000 miles on it at the time. Now that my Tahoe has passed the 100,000 milestone I have been considering switching oil viscosity. Thought about going to the new 0W40 Mobil 1 but have had second thoughts. Newer generation Chevy small blocks have smaller channels than older small blocks. We probably need to stick with 30 weight oil. One good thing about synthetic is that it doesn't break down like Dino oil. The viscosity lasts a long time. I will switch my wife's Suzuki over to 0W40 but not my Tahoe. The 0W40 is better suited to small hi rev engines. I am starting to get some minor seepage in my Tahoe so I will switch over to 10W30 at my next Tahoe oil change. I suggest you do the same. If your Tahoe continues to use oil excessively then you have probems oil viscosity isn't going to fix. You either need to quit hot rodding your Tahoe or you have an internal engine problem. You also might consider changing your coolant every other year regardless of mileage. I have heard numerous horror stories about the Orange stuff gelling and or starting to eat gaskets before the recommended change interval. Better safe than sorry. One other thing. Change your Thermostat to a mid range temperature. 170-180. A cooler running engine generally uses less oil and performs better. I changed mine when I changed to synthetic and have no regrets.

[sa200]

I have a 94 Blazer with 150,000 miles and the 5.7 is like new condition. I have used Lubrication Engineers 10W-30 oil in it since i broke in the motor. Their 10W-30 oil is a High quality blend of synthetic and paraffinic base oils that can go 25,000 miles. They dont believe in 100% synthetic engine oil. (something about,100% synthetic, wont hold all the attitives in it, ect.) But i change it yearly at about 12,000 miles. But during that year i install a new oil filter at 4 and at 8 thousand miles. I cant imagine going back to changing oil and filter at 3000 miles. I know Many people and construction company's that used LE products for years and swear by it. I can honestly say their products are second to none! If there was better products out there,,,,i would'nt hesitate changing.!! I can go on and on but i made my point. As far as you people using the dexcool,,, their recomended interval change should of been cut in half..... Dont trust it beyond 2 1/2yrs, and keep your cooling system full.!!!

just-a-tip.

[MarkWayne]

I have been using Mobile 1 synthetic motor oil in various vehicles since the late 80s. It has never increased my oil consumption in any vehicle so far. I doubt it will decrease your oil consumption unless you run non-synthetic oil more than 3,000 miles. Synthetic oil gets dirty like most non-synthetic oils, but is not affected as much by high temperatures, in my experience. Synthetic oil does not turn dark brown as fast as non-synthetic oil, in my experience. I run it until my engine change oil light comes on. In a northern cold climate 5W-30 might be the better choice and 10W-30 might work better in warmer climates, at least for these newer engines.

Give the synthetic a try. I don't think it will cause any problems. Check your gas mileage before changing over to synthetic. On some of my vehicles, it has increased my gas mileage about 1mpg.

Good Luck,

Mark