Synthetic oil and change intervals

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Jul 26, 2002
New Jersey
I have been using synthetic oil in our family cars and my Harley for more than the last 15 years. For many years now, I have been using Mobil 1 5W-30 in all the family cars and changing at 3,000-4,000 miles and using purolator filters. For the Harley its been Redline 20W-50 and Perf-form filters, with the interval 1500-2000 miles. My thinking has been, for the m/c cost is no object, but for the cars Mobil 1 at $4 is pretty darn good verus the $8/qt Redline. In reading stuff on this website, it seems to suggest that the real premium synthetics do have increased additives permitting a more longer chnage interval. I'm also not getting any younger and if I could cut # of oil changes per year, with no loss in protection, it would be a good thing. So here's my question: Would Redline 10W-30 with changes at 5,000 miles offer the same or better protection as Mobil 1 5W-30 with changes at 3,000. With this approach the cost would be the same as with Mobil. Of course, I'm talking about the cars only.
If Redline has more Zn, P and moly it might. With those change intervals I doubt it. I'd be more concerned with the air filter if you change your oil that often. I like Molakule's idea. 10w30 M1. [ August 09, 2002, 02:23 PM: Message edited by: satterfi ]
Oil analysis is your friend. Use it, and then decide whether M1 is right for you. You might want to also try Mobil Delvac 1 5W40 Synthetic which is readily available in most WalMart outlets. I'm a firm believer that certain oils protect certain engines better than others, and vice versa. This can only be answered using oil analysis though. Regards, Oz P.S. What kind of cars do you currently maintain?
You mention air filters. For the four family cars and the Harley I'm running K&N's. I never really thought twice about filtration, as I was orta believing their claims of about as good as OEM, but in my heart it seemed oiled cotton would be hard pressed to match paper.
Mr. Qz, thanks, the cars are: 2001 Ford F-150 V-6 9,000 miles 1999 Jeep Grand Cherokee 38,000 miles 1995 Jeep Grand Cherokee 117,000 miles 1992 Volvo 940 GL 143,000 miles none burn any oil, prob going to get rid of two oldest within the year.
Is there a section or tutorial on oil analysis on this web site? To use oil analysis for decision making, I figure I'd have to have an analysis of say a Mobil 1 sample at say 3,000 miles. Then let's say I'd also do one with same oil at 5,000 miles. 5,000 is 1.66 times 3,000, so if I saw an increase in the various metals that was more than say double the level at 3,000 miles (with the 5,000 mile sample) , then I'd conclude that the oil was no longer doing its job with the longer interval. Then I'd go on to try a "better" oil. Is this the idea? I was sorta hoping that some of you guys had this all scoped out, and I'd rely on your collective wisdom.
For the four family cars and the Harley I'm running K&N's. I never really thought twice about filtration, as I was orta believing their claims of about as good as OEM, but in my heart it seemed oiled cotton would be hard pressed to match paper.
From what I've seen, it seems to be the application, rather than the filter. Again, analysis is your friend.
msparks has reported high amounts of Silicon (double digits) in his oil analysis using K&N, whereas myself, I'm experiencing a very low amount (4ppm). Like VaderSS said though, it could just be the application...maybe my K&N fits better in Mazda than msparks'. [Off Topic!] question: Where in Jersey are you? I used to live in Jersey City back in the late 80s. Regards, Oz P.S. Please don't call me "Mr.", sounds like I'm old - when in fact I'm probably one of the youngest in this board [Wink]
Ok Oz, I live in Eatontown, New Jersey. Monmouth County and Jersey shore, this is Bruce Springteen country, as he has homes in Rumson and in Colts Neck. Age, hey I'm 55, which is not so bad, but I might have another opinion in ten years, but hey, Bruce is 52! I think the baby boomer generation is redefining getting old.
Dick, Here is my rule of thumb for oil analysis and the protocol has worked well for me. When I am trying/testing a new oil, I sample at 1k, 3k, and 5k. At 5k I determine if the oil could make it to 8k, then sample again at 8k. If I have had previous experience with the oil, I sample evenly at 3k intervals. Why this kind of regime? [Confused] A long time ago when head gaskets were the pits, and the engine manufacturers hadn't figured out how to mate aluminum heads with steel blocks, I determined that 2k-3k was the best an oil could do if I had a gasket leak, or the start of a leak. I decided a spun bearing would cost more to replace than have cheap oil analyses.
Running Mobil 1 at 3k, or Redline at 5k, is actually pretty conservative. You'll probably find (through oil analysis) that both of these oils can go double that interval. Maybe more under ideal conditions.
I have and still use K&N filters or similar cotton gauze filters from PRM or S&B and the one thing most users neglect is to lightly Re-0il the filter about 2 or 3 times a year. K&N suggests this be done although you do not have to clean it very often. I have a spray can of K&N oil just for this purpose. The protective filtering layer of oil does evaporate or get pushed out of the filter over time and miles, reducing the filter's ability to prevent dirt from entering the engine. You can usually see clear areas in the red oil colored gauze on a filter after a few months of use.
I gues I'm the wild one around here. [Smile] With a synth, I push it to the maximum recommended interval ie; 7500 miles, check it, and extend from there.
VaderSS, In my '86 Burb I can go to 8K on a full synth without a hitch. [Cool] But I can't do this for the Nissan Frontier or the '92 Burb with lean burns and hot combustion chambers. As GW said, "JUST CAN'T DO IT; NOT PRUDENT!" [Eek!] [Mad]
Normally I wouldn't test oils before 2 or 3K, because most will easily pass at that point. But I let someone convince me to send in the Name Brand oil they were using at 900 miles to start a test, and it was worse than the worst test I've run on other oils at 4K to 12K. So surprises are always in the wings.
I don't see why Mobil 1 would not easily go 6k. I'm currently using Mobil 1 5w-30 Tri-Syn with a PureOne filter on my wifes 97 Saturn. Notice how I experimented with synthetic oil on the wifes car not my F-150 or the John Deere. Started by running the first batch 3k then sampling and changing. (3k oil changing is a hard habit to break.) Then sampling the next batch at 6k. Currently using the last of my Mobil 1 Tri-Syn 5w-30. Here are the results 3k then 6k. Cu 0,16 Fe 10,17 Cr 1,1 Pb 1,1 Al 2,3 Si 5,11 Mo 1,1 Na 2,8 Mg 1150,1410 Sn 2,1 Zn 649,751 K 0,0 P 540,663 Ca 680,751 Vis 12.4,11.0 no water,fuel or antifreeze I don't see a problem with the 6k numbers. They may have been effected by my cleaning the throttle body during this sampling period. So the old Mobil 1 formula seemed to make 6k easily even in a hostile environment. Oh yes my wife is a granny driver 2 miles to the Post Office one day, 1.5 miles to church the next etc,etc. Really hard on the oil you know, never getting warmed up. Once a week I drive the Saturn 60 miles each way (70mph, ambient temp. 98f) to work 95% country road 5% small town stop and go. The car had 110,000 when I switched to synthetic Mobil 1 5w-30 and PureOne filters. Prior to that 10w-30 Pennzoil with Fram filters every 3k or 3 months which ever came first. Now that Mobil 1 changed formulations I could either start the test over again or change oils altogether. Have decided to give Schaeffer 10w-30 blend a try in both the Saturn and the F-150 and 15w-40 for the John Deere. I'll report my results at 3k and 6k with Schaeffer. By the way Tim Mills has been very helpful and patient.
I'll agree with Patman. Running Red Line at 5,000 mile intervals is fairly conservative. Given it's cost, I'd consider 5,000 miles the shortest interval unless you are driving an exotic and/or turbo car and the extra expense is relatively cheap insurance. I used Red Line for the past year and if you look at my results in the oil analysis section, you'll see it held up pretty well for 7,200 miles in a hard-driven Honda 1.5L 4-cyl. The numbers would be even better 'cept it looks like I have a leaky headgasket. [Frown] --- Bror Jace
The engine will last longer changing the oil at 3,000 miles than it will changing at 5,000 miles. Oil must be changed if it is dirty. If you can keep it clean you will not need to change it. What has worked for me for the last 40 years is to install a filter that cleans oil. The filter gets dirty -- the oil stays clean. You change the filter and keep the oil. Synthetic oil has advantages but doesn't go farther than conventional oil between changes. Ralph
Once again it will be interesting to see if the new SL grades of oil test closer to synthetics than their predecessors. The original poster, Dickflh, was only looking for 5-6k changes. These results are slow in coming. [I dont know]
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