Guest Kingglory Posted October 10, 2009 Share Posted October 10, 2009 What are your opinions? I know GM calls for 5W/30. Does everyone use 5 weight?Dino or Synthetic? :confused: Link to comment Share on other sites More sharing options...
Guest THEHKP7M13 Posted October 10, 2009 Share Posted October 10, 2009 I use synthetic. I catch it on sale so its not that big of an issue. Link to comment Share on other sites More sharing options...
wws944 Posted October 10, 2009 Share Posted October 10, 2009 Synthetic for everything but the lawn mower, though my new-to-me Reatta still has dino in it for now. Walmart has 5 qt jugs of M-1 for $22.For me 5W-30 is fine for the GM cars. The 944 uses 20W-50. But its engine tends to live at much higher RPMs. Link to comment Share on other sites More sharing options...
Guest Kingglory Posted October 10, 2009 Share Posted October 10, 2009 Thanks, I have used nothing but M1 in all my cars. I had my GMC Envoy in for service and I asked the mechanics this same question.They said never use synthetic in an older car with higher mileage?? Due to DINO oil has a larger molecule structure and the 3.8 engine was only designed for regular oil.This did not make much sense to me either....Maybe he should be working as a engineer for NASA and not a Gm dealer, lol. Link to comment Share on other sites More sharing options...
Rawja Posted October 10, 2009 Share Posted October 10, 2009 I've usually used synthetic in everything. The only downside is it's ability to "find" leaks. Once switched and leaks eliminated everything's cool. I've had no issues switching with a number of cars with over 100K. Link to comment Share on other sites More sharing options...
charlie1 Posted October 10, 2009 Share Posted October 10, 2009 It really "finds" leaks in the Northstar. Had the powertrain removed on a 1999 and a 2001 after switching to Mobil 1. Link to comment Share on other sites More sharing options...
padgett Posted October 10, 2009 Share Posted October 10, 2009 I have always used Dino in street cars, change too often for synthetic to be useful. Always use 10w-30 since it does not get cold here. Castrol GTX "Hi-Milage" (5 qt jug for $13) lately.Would like to know why when gas prices came down, oil didn't & why synthetic went up also.ps just wait until the hyperinflation starts. Watch for the fed to bring back the $500 and $1000 dollar bills. Link to comment Share on other sites More sharing options...
Guest kennyw Posted October 10, 2009 Share Posted October 10, 2009 Guys:> after viewing this link you will find you know less about motor oil then ever.......kenAll About Motor Oil Link to comment Share on other sites More sharing options...
charlie1 Posted October 10, 2009 Share Posted October 10, 2009 (edited) If you like to discuss oil their is a website that I read on occasion bob is the oil guy Edited October 10, 2009 by CHAS1 (see edit history) Link to comment Share on other sites More sharing options...
wws944 Posted October 10, 2009 Share Posted October 10, 2009 It really "finds" leaks in the Northstar. Had the powertrain removed on a 1999 and a 2001 after switching to Mobil 1.Don't some Caddys come factory-filled with synthetic oil? Link to comment Share on other sites More sharing options...
Guest Richard D Posted October 10, 2009 Share Posted October 10, 2009 Here in South Florida I have used dino 10-30W in everything except my first car, a 1965 Marlin with a Rambler 327-4BBL. It ran on straight 30W. I also change the oil and Pur-One filter every 4 K miles or so. Have never had an oil related problem, using oil, valve guides, bearing wear, leaks, etc. Link to comment Share on other sites More sharing options...
charlie1 Posted October 10, 2009 Share Posted October 10, 2009 Don't some Caddys come factory-filled with synthetic oil? Yes the newer ones, we traded the 1999 SLS on a 2008 STS and it requires Mobil 1. It is a V-6 so it does not have all those sealing areas on the lower end prone to leaking like the Northstars do Link to comment Share on other sites More sharing options...
Guest steveskyhawk Posted October 11, 2009 Share Posted October 11, 2009 If synthethetic oil "finds" leaks then it means that you had leaks plugged up by sludge and that lubrication is getting to places that went unlubricated with dino. You get what you pay for. Link to comment Share on other sites More sharing options...
Guest F14CRAZY Posted October 13, 2009 Share Posted October 13, 2009 With the supercharged LN3 I switched to Mobil 1 at around 153k. I didn't really experience any more leaking.At about 163k I dropped the oil pan and found that the screen on the oil pickup was mostly clogged with junk. How that happened, I don't know. It could have been from the synthetic loosening up sludge (which i think is very possible) but oil pressure always read fine and the engine was holding up just fine according to oil lab analysis. It's hard to say whether this was an isolated dino-to-synthetic switch or not. Link to comment Share on other sites More sharing options...
Guest F14CRAZY Posted October 13, 2009 Share Posted October 13, 2009 Also was going to say too, I don't think its exactly needed but during the summer I tend to run 10/30 and 5/30 in colder weather Link to comment Share on other sites More sharing options...
padgett Posted October 13, 2009 Share Posted October 13, 2009 Weren't early synthetics something like 5W-15, could account for the leaks. Link to comment Share on other sites More sharing options...
wws944 Posted October 13, 2009 Share Posted October 13, 2009 Weren't early synthetics something like 5W-15, could account for the leaks.Like 30 years ago, Mobil had some problems. But they quickly added some sort of seal conditioning additive to fix it.An engine which could have made good use of synthetic was my long-gone '78 Turbo Regal. The turbocharger was oil cooled, and was really hard on oil due to the heat and narrow clearances. Back then the SC grade oils really did need to be changed religiously at 3K miles - especially with the turbo. A lot of neglectful owners found out the hard way. Link to comment Share on other sites More sharing options...
Guest barra Posted October 17, 2009 Share Posted October 17, 2009 I have substituted a quart of Lucas oil additive at each change. I drive less than 3000 miles a year on each change. So far, no leaks or rattles on start-up. Link to comment Share on other sites More sharing options...
Guest Richard D Posted October 17, 2009 Share Posted October 17, 2009 (edited) I try to drive the Skylark around once a week for about 20-30 minutes to keep the Florida humidity out of the engine oil and tranny fluid. Sometimes it is every two weeks. It also keeps the A/C lubricant on the compressor seal. Does anyone have any thoughts on a low power oil pan heater to keep the oil around 110 degrees F.? I know I would lose the tranny fluid and A/C lubricant benifits. Edited October 17, 2009 by Richard D (see edit history) Link to comment Share on other sites More sharing options...
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