Running Synthetic in a older high mileage engine?

[bigreen505]

If I were to swith my 97 Nissan w/ 120k to synth this season, is there a 'flush' recomendation? Such as run put in synth for 1000 miles, and drain/fill, then go the 5000?

There are two types of motor flush you can buy -- one that is kerosene and one that is just a super thin synthetic oil. I have used both, but I am a lot more comfortable with the thin oil. Basically just dump it in, let the engine idle for a while and drain. I replaced the first round of synthetic at 5,000, then switched to 10,000 mile intervals.

I just realized that I forgot to flush with the Trooper, but I only had about 4,000 on the new engine.

 

[rgsiii]

The only way to tell what will happen is to try it. Not all synthetics are the same. My '94 LC used excessive amounts of most of the Mobil1 oils, but did fine on what was their SUV/truck flavour (I believe it is something like 10/40) and now is their diesel one. I now use Rotella synthetic without problems.

 

[Pskhaat]

Go for it. Synthetics make a lot of sense to me.

Personally, I only change my synthetic oil in all my vehicles once a year regardless of mileage. Once a year I also send in my oil for analysis, and I have been able to maintain outstanding results.

I'm sure Amsoil is very good stuff, as well as Royal Purple and Redline, I've never heard bad things about any of them. One anecdotal note however being an Oil Brat: the major oil companies use Mobil lubricants for their own equipment. There are many stories about rigs and pumps where the companies' own lubricants are either given away or sold and Mobil lubricants are silently used from petty cash funds.

 

[Erick Lihme]

Before running it in Toyota manual trans, check the specs. For example, G52 and W56 as well as many other Toyota transmissions require GL4/GL5. A gear lube which is rated as a GL5 only, has additives which may erode the brass syncos.
Read the label. Royal Purple 75w-90w, and Redline MT90 are two which have a GL4/GL5 rating. Diffs requiring a hypoid oil might be best served with a Redline oil as it needs oil which clings, and provides ample cushioning. I am partial to Redline in gear boxes. One can email Redline to get their recommendations. Synthetics are THE way to go in very cold climates. A standard 10w-30 may have a pour point at about 30-35 below zero. Mobil 1 would have a pour point at -58 below. Much easier cranking is noticable even above 0 degrees. The same goes for gear oil. With Dino oil in the box, it it feels like the brake is on, but no so with a synthetic.

There is a risk when changing over to synthetic in a high mileage motor, especially in which has not been served adequately, as sluge and varnish build up on worn and hard seals can help prevent seepage. A synthetic oil is highly detergent and can remove that build up. This may not as an important factor if the motor was run a Dino oil which itself was highly detergent and/or change regularly. That said, my personal experience has been good.

I totally lucked out last year on a purchase of 85' EFI 2WD extra cab auto pickup with only 53K. Cherry! They are still out there! The 80 year old fellow couldn't drive anymore. It had been poorly serviced and sat in the garage for years. The diff oil had actually separated and the seals leaked. All other was good, but the timing chain rattled excessively on start up. Mobil 1 apparently cleaned out the timing chain tensioner, and she rattles no more. And just as important, eventho I expected it to leak like crazy, there has been no leaks and does not burn it.

 

[Diesel Joe]

IF there is a problem that using synthetic brings to the surface, (it is VERY slick and often causes leaks in old engines) then that's a problem you NEEDED to fix in the first place. There is nothing bad about synthetic oil.... Save maybe the cost in comparrison to dyno oil. It has been being run in old and new diesel engines around here for twenty years!


That's the thing about synthetic oil. With proper filtration you CAN safely extend drain intervals. If youre going to go much beyond 5000klm you should change your oil filter so that the extended oil gets good filtration. What you should do is add in a bypass engine oil filter. The standard oil filter passes 100% of the oil ever 60 seconds or so. The bypass filter passes the oil every ten minutes or so. A standard oil filter is good for around 25+ microns. Many bypass oil filters are good for LESS than 4 microns!!!!

 

[Erick Lihme]

PRODUCT DESCRIPTION
The Ea By-Pass Oil Filter (EaBP) provides the best possible filtration protection against wear and oil degradation. Working in conjunction with the engine’s full-flow oil filter, the AMSOIL Ea By-Pass Filter operates by filtering oil on a “partial-flow” basis. It draws approximately 10 percent of the oil pump’s capacity at any one time and traps the extremely small, wear-causing contaminants that full-flow filters can’t remove. The AMSOIL Ea Bypass Filter typically filters all the oil in the system several times an hour, so the engine continuously receives analytically clean oil.

http://www.amsoil.com/storefront/SearchResult.aspx?CategoryID=77

 

[Mike S]

I have run Mobil 1 in all my vehicles for years. When I bought my FJ60, the owner had run dino in it, and I switched to Mobil 1 - no leaks after the change.

My FZJ80 used Catrol Syntec from the beginning, and I recently switched to Mobil 1. Again, no leaks.

I have used Mobil 1 in my Ford F250 Deisel, My Ford Explorer, both My Landcruisers, my Maserati, and my Ford Expedition. Some of these vehicles had some extreme miles on them, but no problems. My son-in-law drove my Explorer home after blowing the bottom radiator tank - it was dry and HOT when he got home. The shop had to mill the head because of warpage, but they reported zero problems with the block, crank, bearings, etc. My daughter drove that little truck for over 150,000 miles after that incident. So I believe that synthetics are money well spent.

 

[Erick Lihme]

Interesting: Mobil 1 vs. Amsoil tests

http://neptune.spacebears.com/cars/stories/amsoil.html

 

[Grim Reaper]

http://neptune.spacebears.com/cars/stories/amsoil.html

Curious to see what the next mobile 1 test shows now that the motor is worn in.

I have TWICE on two different motor run into leak issues when I went to Synthetic. The first was on a 350 Chevy that started leaking around the mechanical fuel pump and out of both valve covers and it was MAJOR leaking. The motor was relatively dry before that. That was Syntec that time. I did notice and improved MPG and went to a 6k change interval. After new valve cover gaskets and pump gasket I didn’t have any other leak issues. Motor have about 80k when this happened.

The second time is on my 454 Suburban. This time with Mobile1. The valve covers were already seeping a little and the Mobil1 made it worse. That truck see’s very few miles (under 3k last year) I change yearly more out of fear of condensation in the block then anything else.

I have in the past run the Redline MT90 in a Toyota W58 (N/A supra) and noticed a BIG improvement in shift feel. The W56 (nearly identical to the W58) in my 4Runner has Mobile1 in it and I have noticed it is a little notchy. It have about 5k on it now after a full rebuild. After the post about the Redline and Toy tranny’s I think I may switch it to Redline since I previously had good results.


In the last 2- 3 years I have been going through my truck and rebuilt the engine transmission and now the rear end when I swapped in a E-Locker. Everything is about broke in now. Next change on everything but the front diff is going Synthetic. Probably Mobil1 on everything but the Transmission since it is the easiest to get for me (they have it at Autozone). Try the Redline again in the transmission.

 

[Erick Lihme]

Royal Purple 75-90w GL4/GL5 in cooler tempatures seems fine. As we are going into summer, the shifter felt 'notchy' and a slight bearing noise could be heard in 5th under pressure, where the dino oil, 80-90w GL4 was replaced by the Royal Purple at the onset of winter, the Vavoline felt good at all temps, and no bearing noise was heard.
The Royal Purple was replaced with the dino oil until I get around to the MT90. Again with dino oil, the bearing noise went away.

Given how Royal Purple seemed to do in the trans, the diff's may get one of the other GL5 Redline heavier gear oils. I've read that the MT90 does best in the W56 trans because it is thicker.